VENTILATION  i  HEATING 


BY 


JOHN  S.    BILLINGS,  A.  M.,   M.  D., 

LL.D.  EDINBURGH  AND  HARVARD.     D.  C.  L.  OXON.     MEMBER  OF 

THE    NATIONAL    ACADEMY    OF    SCIENCES. 

SURGEON,  U.  S.  ARMY,  ETC. 


NEW    YORK: 

ENGINEERING     RECORD, 

(Prior  to  iSSj  The  Sanitary  Engineer.) 
1893. 


Entered  according  to  Act  of  Congress,  in  the  year  1892,  by 

THE  ENGINEERING  RECORD, 
In  the  Office  of  the  Librarian  of  Congress,  at  Washington,  D.  C. 


PREFACE. 


IN  preparing  this  volume  my  object  has  been  to  produce  a 
book  which  will  not  only  be  useful  to  students  of  Architect- 
ure and  Engineering,  and  be  convenient  for  reference  by  those 
engaged  in  the  practice  of  these  professions,  but  which  can 
also  be  understood  by  non-professional  men  who  may  be 
interested  in  the  important  subjects  of  which  it  treats;  and  hence 
technical  expressions  have  been  avoided  as  much  as  possible, 
and  only  the  simplest  formulae  have  been  employed.  It 
includes  all  that  is  practically  important  of  my  book  on  the 
Principles  of  Ventilation  and  Heating,  the.  last  edition  of  which 
appeared  in  1889  ;  but  it  is  substantially  a  new  work,  with 
numerous  illustrations  of  recent  practice.  For  many  of  these 
I  am  indebted  to  THE  ENGINEERING  RECORD,  in  which  the 
descriptions  first  appeared. 

I  am  also  indebted  to  Dr.  A.  C.  Abbott  for  much  valuable 
assistance  in  its  preparation,  and  to  the  architects  and  heating 
engineers  who  have  furnished  me  with  plans  and  information, 
and  whose  names  are  mentioned  in  connection  with  the 
descriptions  of  the  several  buildings,  etc.,  referred  to  in  the  text. 

JOHN  S.  BILLINGS. 

Washington,  D,  C., 
January,  1893. 


no  /i  /f  c\ 


TABLE  OF  CONTENTS. 


PAGE 

CHAPTER  I  —Introduction.     Utility  ot  Ventilation 17 

CHAPTER  II.— History  and  Literature  of  Ventilation 26 

CHAPTER  III.— The  Atmosphere:  Composition  and  Physical  Properties.  42 

CHAPTER  IV.— Carbonic  Acid 61 

.  CHAPTER  V.— Conditions  Which  Make  Ventilation  Desirable  or  Neces- 
sary. Physiology  of  Respiration.  Gaseous  and  Particulate  Impu- 
rities of  Air.  Sewer  Air.  Soil  Air.  Dangerous  Gases  and  Dusts  in 
Particular.  Occupations,  or  Processes  of  Manufacture.  Drying 
Rooms • 85 

CHAPTER  VI.— On  Moisture  in  Air,  and  Its  Relations  to  Ventilation. . .    114 

CHAPTER  VII.— Quantity  of  Air  Required  for  Ventilation. . . ! 120 

CHAPTER  VIII.— On  the  Forces  Concerned  in  Ventilation. 137 

CHAPTER  IX.— Examination  and  Testing  of  Ventilation 161 

CHAPTER  X.— Methods  of  Heating:  Stoves,  Furnaces,  Fireplaces,  Steam 

and  Hot- Water  Thermostats 208 

CHAPTER  XI.— Sources  of  Air  Supply.     Filtration  of  Air.     Fresh-Air 

Flues  and  Inlets.     By-Passes 247 

CHAPTER  XII.— Foul- Air  or  Upcast  Shafts.     Cowls.     Syphons 273 

CHAPTER  XIII.—  Ventilation  of  Mines..  .  288 


VIII  TABLE    OF    CONTENTS. 

PAGE 

CHAPTER  XIV.— Ventilation  of  Hospitals  and  Barracks.  Barrack  Hos- 
pitals. Hospitals  for  Contagious  Diseases.  Blegdams  Hospital. 
U.  S.  Army  Hospitals.  Cambridge  Hospital.  Hazleton  Hospital. 
Barnes  Hospital.  New  York  Hospital.  Johns  Hopkins  Hospital. 
Hamburg  Hospital.  Insane  Asylums.  Barracks ....  301 

CHAPTER  XV.— Ventilation  of  Halls  of  Audience  and  Assembly  Rooms. 
The  Houses  of  Parliament.  U.  S.  Capitol.  The  New  Sorbonne. 
The  New  York  Music  Hall.  The  Lenox  Lyceum 355 

CHAPTER  XVI. —Theaters.  Air  in  Manchester  Theaters.  Grand  Opera 
House  in  Vienna.  Opera  House  at  Frankfort-on-the-Main.  Metro- 
politan Opera  House,  New  York.  Madison  Square  Theater. 
Academy  of  Music,  Baltimore.  Pueblo  Opera  House.  Empire 
Theater,  Philadelphia 379 

CHAPTER  XVII.— Churches 402 

CHAPTER  XVIII.— Schools 4IO 

CHAPTER  XIX.— Dwellings 442 

CHAPTER  XX.—  Ventilation  of  Tunnels.  Railway  Cars.  Ships.  Prisons. 

Shops.     Stables.     Sewers.     Cooling  of  Air.     Conclusion 478 


LIST  OF  ILLUSTRATIONS. 


PAGE 

FIGURE    i  AND  2. — Sections  of  blowing  wheel  or  fan  in  House  of  Com- 
mons in  1736  30 

3. — Illustration  of  rate  of  efflux  between  gases  of  different  den- 
sities   55 

"         4. — Illustrating  the  tendency  of  a  current  from  the  cooler, 

denser,  to  the  warmer,  rarer  body 58 

"         5  .—Illustrating  the  result  of  the  tendency  in  Fig.  4 60 

"         6. — Plan  of  lecture  room.  Columbia  College,  N.  Y.,  showing 

ventilation 152 

"         7. — Section   through  coil  box,  in  cellar  of  Columbia  College, 

N.  Y ..  153 

"         8  — Plan  of  coil  and  exhaust  shaft  of  Columbia  College,  N.  Y. .  154 

"         9. — Section  of  coil  and  exhaust  shaft  of  Columbia  College,  N.  Y.  155 

10. — Casella's  anemometer '162 

•ii,  12  AND  13. — Improvised  anemometer 167 

"       14  AND  15. — Fuess's  anemometer 168 

"       16. — Wolpert's  air  tester 177 

"       17. — Wolpert's  carbacidometer.    178 

18. — Lunge-Zeckendorf's  apparatus  for  determining    carbonic 

acid  in  the  air 181 

"        19. — Flask  for  barium  in  solution 186 

20. — Pettenkofer's  apparatus  for  aspiration  of  air  through  baryta 

water 191 

21. — Szydlowski's  apparatus  for  determining  the  amount  of  car- 
bonic acid  in  the  air 192 

22. — Reiset's  apparatus  for  determining  the  amount  of  carbonic 

acid  in  the  air 196 

23. — Baker,  Smith  &  Co.  's  radiator 223 


X  LIST    OF    ILLUSTRATIONS. 

PAGE 

FIGURE  24. — Showing  manner  of  bringing  air  to  the  base  of  a  direct- 
indirect  radiator 236 

25. — Baldwin's  radiator  for  Moses  Taylor  Hospital 237 

26. — Appold's  automatic  heat  regulator 242 

27,  28,  29  AND  30. — Thermostat  in  Mechanics'  Bank,  New  York. 

243,  244,  245,  246 

31. — Dust  arrester 248 

32. — Radiators  in* the  Laboratory  of  the  University  of  Pennsyl- 
vania    249 

33- — Jeffrey's  plan  of  utilizing  the  heat  of  the  earth  in  heating 

and  ventilating 251 

34. — Sheringham  ventilation  valve , 257 

35- — Window  ventilator,  external  view 259 

36. — Window  ventilator,  section 260 

37. — Gillis  &  Geohegan  switch  valve  for  heating  coils 261 

38. — Baker,  Smith  &  Co.,  switch  valve  for  heating  coils 262 

39. — C.  W.  Newton  switch  valve  for  heating  coils 263 

40. — Switch  valve  used  at  Johns  Hopkins  Hospital,  Baltimore. .  264 

41. — N.  Folsom's  switch  valve  for  heating  coils 265 

42. — A.  Mercer's  switch  or  "mixing  valve." 266 

"       43. — Plan  and  section  of  "  mixing  register." 267 

"       44  AND  45. — Sections  of  Baldwin  mixing  register  in  Orthopaedic 

Hospital,  N.  Y 268,  269 

"       46. — Baldwin's  mixing  register  at  College   of  Physicians  and 

Surgeons,  N.   Y 270 

"       47. — Cross-section  of  A.  C.  Abbott's  by-pass  radiator 271 

"       48,  49  AND  50. — Plan  and  sections  of  aspirating  chimneys,  Johns 

Hopkins  Hospital 277 

"       51. — De  Lyle  St.  Martin's  chimney  top  ventilator 281 

52. — Cisalpin's  chimney  top  ventilator 281 

"       53. — Emerson's  chimney  top  ventilator,  slightly  modified 281 

"       54. — Chimney  top  ventilator 281 

"       55. — M'Kinnell  "inlet  and  outlet  ventilator." 284 


LIST    OF    ILLUSTRATIONS.  XI 

PAGE 

FIGURE    56. — Barker's  heating  apparatus  with  combined  inlet  and  outlet. . .     285 

57. — Ventilating  mine  by  shaking  a  piece  of  cloth 289 

58. — Ventilating  fan  of  1556 294 

59. — Construction  of  fan  of  1556 295 

60. — Cross-section  of  Root's  blower,  Chilton  Colliery,  England.  296 

61. — Cross-section  of  St.  Petersburgh  City  Hospital 302 

62. — Floor  plan  of  St.  Petersburgh  City  Hospital 303 

63. — Cellar  plan  of  St.  Petersburgh  City  Hospital 303 

"         64,65,66  AND  67.— Plans  of  small-pox  hospital,  Bradford,  England  305 

«<         68. — B.  Sanderson's  plan  for  small-pox  hospital 306 

"         69,  70  AND  71. — Plans  of  ward  for  infectious  diseases,  Blegdams 

Hospital,  Copenhagen 307-9 

72. — Isolating  ward,  Johns  Hopkins  Hospital. . .    . 309 

73*  74.  75  AND  76. — Details  of  isolating  ward  of  John^  Hopkins 

Hospital 310 

77. — Basement  plan  of  small  U.  S.  Army  Hospital 311 

78. — Floor  plan  of  a  small  U.  S.  Army  Hospital  312 

79. — Basement  plan  of  U.  S.  Army  Hospital  of  24  to  48  beds. .  313 

80. — Floor  plan  of  U.  S.  Army  Hospital  of  24  to  48  beds 324 

81. — Basement  plan  of  Cambridge  Hospital 315 

82. — First  and  second-floor  plan  of  Cambridge  Hospital 316 

83. — Section  of  hot-air  box,  Cambridge  Hospital 318 

84. — Perspective  elevation  of  hot-air  box,  Cambridge  Hospital.  318 

85. — Basement  plan  of  Isabella  McCosh  Hospital 320 

86. — First-story  plan,  Isabella  McCosh  Hospital 321 

87. — Second-story  plan,  Isabella  McCosh  Hospital 322 

88. — Section  through  radiator,  Isabella  McCosh  Hospital 323 

89. — Sectional  perspective  of  radiator  case 323 

90  AND  91. — Sections  of  radiator  case 324 

92. — Basement  plan  of  Miners'  Hospital,  Hazleton,  Pa 325 

93. — First-story  plan  of  Miners'  Hospital,  Hazleton,  Pa 326 

94. — Barnes  Hospital  at  Soldiers'  Home,  Washinghton,  D.  C. . .  327 

95. — First  and  second-story  plans  of  Barnes  Hospital 329 


XII  LIST    OF    ILLUSTRATIONS. 

PAGE 

FIGURE    96. — Cellar  plan  of  New  York  Hospital  Building 332 

97. — Second-story  plan  of  New  York  Hospital  Building 334 

98. — Diagram  of  ventilation  and  heating  of  New  York  Hospital 

Building 335 

99. — Block  plan  of  Johns  Hopkins  Hospital 336 

"        100. — Floor  plan  of  common  ward,  Johns  Hopkins  Hospital. . . .  337 
"        101. — Basement  and  attic  plans  of  common  ward,  Johns  Hopkins 

Hospital 337 

"        102. — Longitudinal   section   of  common   ward,    Johns   Hopkins 

Hospital 338 

103. — Cross-section  of  common  ward,  Johns  Hopkins  Hospital. .  339 

"       104. — Transverse  section  of  service  building  of  common  ward. . .  340 

105. — Longitudinal  section  of  octagon  ward 341 

"        106. — Transverse  section  through  water  closets 342 

"        107. — Main-floor  plan  and  transverse  section  of  pay  ward 343 

108. — Longitudinal  section  of  pay  ward 344 

109. — Transverse  section  of  pay  ward 344 

no. — Basement  plan  of  City  Hospital  near  Hamburg 345 

in. — Main-floor  plan  of  City  Hospital  near  Hamburg 345 

"       112. — Longitudinal  section  of  City  Hospital  near  Hamburg 345 

113  AND  114. — Transverse  sections  of  City  Hospital  near  Hamburg.  346 
115. — Half  basement  and  half  first-story  plan  of  Insane  Asylum 

for  New  Castle  County,  near  Wilmington,  Del 347 

116. — Section  through  front  hall  of  New  Castle  County  Insane 

Asylum 348 

"        117. — Section  through  rear  hall  of  New  Castle  County  Insane 

Asylum 349 

1 1 8. — Plan   of  indirect  heaters   and  heat-flues  of   New    Castle 

County  Insane  Asylum 350 

"        119. — First-floor  plan  of  half  of  a  two-story  barrack  for  infantry.  352 

"        1 20. — Second-floor  plan  of  half  of  a  two-story  barrack  for  infantry.  353 
"        121. — Quartermaster  Department,  floor  plan  of  half  of  double 

barrack 354 


LIST    OF    ILLUSTRATIONS.  XIII 

PAGE 

FIGURE  122. — Sectional  elevation  of  the  House  of  Lords 357 

««        I23. — Horizontal   section   through   equalizing  chamber    of    the 

House  of  Lords 35§ 

124. — Horizontal  section  through  House  of  Commons 359 

125. — Plan  showing  air  ducts,  etc.,  in  connection  with  heating 

apparatus,  'south  wing,  U.  S.  Capitol 365 

I26. — Transverse  section  through  south  wing,  U.  S.  Capitol 366 

127. — Section  through  air  ducts  and  heating  apparatus  of  south 

wing,  U.  S.  Capitol 368 

128. — Section  of  amphitheater  of  the  new  Paris  Sorbonne 370 

I29. — General  vertical  section  of  Carnegie  Musical  Hall,  New 

York 372 

"        i^o — Heating,  cooling  and  blowing  plant  of  Carnegie  Hall 373 

131. — Bottom  of  fresh-air  shaft  with  its  outlets  of  Carnegie  Hall.  374 

I32. — Perspective  view  of  fresh-air  shaft  of  Carnegie  Hall 375 

"        I33> — Section  showing  inlet  to  blower  and  check  valve 375 

134. — Basement  plan  of  Lenox  Lyceum,  New  York 376 

135. — Plan  of  Grand  Opera  House,  Vienna 382 

I36. — Section  of  Grand  Opera  House,  Vienna 383 

137. — Ground  plan  of  Metropolitan  Opera  House,  New  York  City .  384 

138. — Longitudinal  section  of  Metropolitan  Opera  House 385 

««        I3g. — Transverse  section  of  Metropolitan  Opera  House 387 

140. — Evaporating  pan  to  regulate  hygrometric  state  of  air 389 

"        141. — Manner  of  admitting  air  through  auditorium  floor.      ...  389 

142. — Section  and  plan  of  private  box 390 

I43. — Ventilation  of  footlights 391 

144. — Ground  floor  of  Pueblo  Opera  House,  Pueblo,  Col 394 

145. — Second  floor  of  Pueblo  Opera  House,  Pueblo,  Col 395 

"        146. — Section  of  stage  and  auditorium 396 

147. — Diagram  plan  of  air  ducts 397 

148. — Plan  of  fan  chamber  and  coil  room 398 

149. — Elevation  at  Z  Z  of  fan  chamber  and  coil  room 398 

150. — Floor  plan  of  Empire  Theater,  Philadelphia 399 


XIV  LIST    OF    ILLUSTRATIONS. 

PAGE 

FIGURE  151. — Vertical  section  of  Empire  Theater,  Philadelphia. 400 

"        152. — Basement  plan    of    Fifth  Avenue  Presbyterian  Church, 

New  York 403 

"        153. — Longitudinal    section     of     Fifth     Avenue     Presbyterian 

Church,  New  York 405 

154. — Plan  of  Hebrew  Temple,  Keneseth-Israel,  Philadelphia.. .  407 

"        155. — Vertical  section  of  coil  chamber,  Bridgeport  School 419 

156. — Vertical  section  of  school  building,  Bridgeport,  Conn. ..    .  420 
"        157. — Dr.    Lincoln's   examination   of   ventilation  in  Bridgeport 

School 421 

158. — Ground-floor    plan    of  Jackson   School   building,    Minne- 
apolis    423 

159. — Main-floor  plan  of  Jackson  School  building,  Minneapolis. .  424 

"        160. — Section  of  boiler  room 425 

161.— Plan  of  boiler  room 425 

"        162. — Method  of  setting  Joy  draft  tube  radiator ...  426 

"       163. — Basement  plan  of  Garfield  School,  Chicago 427 

164. — Basement  plan  of  old  part  of  Garfield  School 429 

165. — First-story  plan  of  old  part  of  Garfield   School,  showing 

original  arrangement. 430 

"       1 66. — First-story  plan  of  old  part  of  Garfield  School,  showing 

present  arrangement    43 1 

"       167. — Part   of  basement    containing   heating   apparatus,  Bryn 

Mawr  School,  near  Philadelphia 432 

168. — Part  of  first  and  second  floors,  Bryn  Mawr  School 433 

"        169. — Part  of  third  floor,  Bryn  Mawr  School 434 

170. — General  cellar  plan  and  vertical,  longitudinal  section  of 

College  of  Physicians  and  Surgeons,  New  York  City. . .  435 
41        171. — Ventilating     cornice     in     College     of     Physicians     and 

Surgeons 437 

"        172. — Fourth-story  ventilating  cornices 437 

"        173. — Plan  of  space  between  ceiling  and  roof  showing  ventilating 

ducts 438 


LIST    OF    ILLUSTRATIONS.  XV 

PAGE 

FIGURE  174. — Vertical  sections  of  rooms  showing  foul-air  ducts 439 

175. — Perspective  view  of  direct-indirect  hot- water  radiators 440 

"        176. — Section  of  one  of  the  radiators 440 

"        177  AND  178. — Showing  admittance  of  fresh  air 441 

179. — Hot-water  system   of  heating   in  cellar  of  Prof.  W.    M. 

Sloane,  Princeton,  N.  J 444 

1 80. — Radiator  in  library 445 

"        181. — Cross-section  of  radiator  in  library 446 

182. — Wooden  base  to  inclose  flow  pipe  of  chamber  radiator 446 

183. — Heating  and  ventilation  in  Mr.   Onderdonk's  residence, 

Wyncote,  Pa 447 

184. — Cellar  plan  of  Mr.  Onderdonk's  residence 448 

185. — First-story  plan  of  Mr.  Onderdonk's  residence 449 

"        1 86. — Second-story  plan  of  Mr.  Onderdonk's  residence 450 

187. — General  A.   C.    McClurg's  residence,  Chicago,  foundation 

plan 45 1 

1 88. — General  A.  C.   McClurg's  residence,  Chicago,    basement 

plan 452 

189. — General   A.  C.    McClurg's   residence,  Chicago,  first-floor 

plan 453 

190. — General  A.  C.  McClurg's  residence,  Chicago,  second-floor 

plan . .  454 

191.— General  A.   C.   McClurg's  residence,    Chicago,  third-floor 

plan 455 

"        KJ2. — Mr.  W.  A.  Fuller's  residence,  Chicago,   111.,  plat  showing 

boilers  in  barn 455 

"        193. — Mr.  W.  A.  Fuller's  residence,  Chicago,  111.,  cellar  plan. . .  .  456 
"        !g4. — Mr.    W.   A.   Fuller's   residence,    Chicago,    111.,    first-story 

plan 457 

195. — Mr.  W.  A.   Fuller's  residence,  Chicago,  111.,  second-story 

plan 458 

"        196. — Basement,  second  and  third-floor  plans  of  a  city  residence.  459 

"        197. — First  floor  of  a  city  residence 461 


XVI  LIST    OF    ILLUSTRATIONS. 

f  PAGE 

FIGURE  198  — Basement  plan-of  .house  of  Air.  S.  L.  George,  Watertown, 

N.  Y ...:....:". 463 

"        199. — Arrangement  of  syphons 463 

200. — Arrangement  of  indirect  stacks 463 

201. — Cellar  and  first-story  plan  of  Mr.  W.  H.  Carrick's  house, 

Toronto,  Canada 465 

202. — Second-story  and  attic  plan  of  same 466 

"       203. — Showing  skeleton  apparatus  of  pipes  and  radiators 467 

"       204. — Plan  of  basement 469 

205  — Section  showing  mode  of  admission  of  fresh  air 469 

"       206. — Metal  screen  as  affording  an  aid  to  ventilation 474 

207. — Air  currents  through  open  windows  near  stove 475 

"       208. — Air,  warmed  by  contact  with  stovepipe,  brought  in 475 

"       209. — Showing  how  a  stovepipe  may   assist    in     removing   in- 
jurious air 476 

"       210. — Cross-section  of  New  York  State  Reformatory,  Elmira. . .  .  486 


CHAPTER  I. 

INTRODUCTION.       UTILITY    OF    VENTILATION. 

VENTILATION,  in  the  sense  in  which  the  word  is  used  in  this 
book,  is  the  continuous,  and  more  or  less  systematic,  changing  or 
renewal  of  the  air  in  a  room  or  other  closed  space.  In  simple  aera- 
tion of  a  room  the  air  is  changed  but  once,  or  at  intervals,  while 
ventilation  implies  that  the  change  is  constantly  going  on  by  the  pass- 
ing out  of  a  portion  of  the  enclosed  air  and  the  entrance  of  other  air 
to  take  its  place.  It  is  employed  and  provided  for  in  order  to  remove 
substances  which  become  diffused  or  suspended  in  the  air  while  it  is 
in  the  enclosure,  to  replace  the  oxygen  which  has  been  consumed 
therein,  and  in  some  cases  to  effect  a  change  of  temperature. 

While  it  may  be  required  in  some  cases  chiefly,  or  exclusively,  to 
remove  watery  vapor,  as  in  the  drying  rooms  of  a  factory,  or  to  keep 
an  uninhabited  room  free  from  dampness,  or  to  remove  offensive  or 
dangerous  gases  or  foul  odors  generated  by  either  natural  or  manu- 
facturing processes,  it  is  most  usually  employed  to  dilute  and  remove 
the  products  of  exhalation  and  respiration  of  living  animals,  especially 
of  man,  and  the  products  of  combustion  due  to  heating  and  illumi- 
nating apparatus,  and  to  prevent  the  temperature  of  a  room  from  rising 
above  the  degree  which  is  requisite  to  secure  comfort  and  health. 

It  involves  the  introduction  of  the  comparatively  pure  external 
air  in  continuous  currents,  the  diffusion  of  this  air  throughout  the 
room,  and  the  constant  removal  of  a  corresponding  volume  of  the 
air  which  has  become  contaminated  by  vapors,  gases,  particulate 
matters  or  odors,  or  which  has  had  its  temperature  raised  within  the 
apartment. 

In  studying  the  subject  of  ventilation,  therefore,  we  have  to  con- 
sider the  chemical  and  physical  qualities  of  the  air,  the  various  sources 
of  the  changes  in  its  composition  which  necessitate  its  renewal,  the  forces 
which  are  available  to  cause  its  motion  in  the  direction  best  suited  for 
the  purpose,  and  the  arrangement  of  openings,  ducts,  flues,  shafts, 
etc.  which  are  best  adapted  to  secure  the  entrance,  diffusion  and  exit 
of  the  quantity  of  air  required. 


l8  UTILITY    OF    VENTILATION. 

When  the  quantity  of  air  to  be  supplied  has  been  determined, 
the  general  principles  which  should  govern  the  arrangements  in  a  room 
or  building  to  secure  the  satisfactory  introduction  and  distribution  of 
this  air  are  comparatively  simple,  but  their  practical  application 
requires  a  special  study  of  the  circumstances  of  each  individual  build- 
ing to  secure  the  best  results. 

The  great  majority  of  human  habitations  in  cold  climates  have 
no  special  provisions  for  ventilation  during  that  part  of  the  year  in 
which  artificial  heat  is  required,  and  even  in  the  majority  of  large  and 
costly  public  buildings  such  as  churches,  opera  houses,  State  capitols, 
court  rooms,  assembly  halls,  school  houses  and  hospitals,  in  which,  of 
late  years  at  least,  it  -is  usual  to  introduce  some  openings  and  flues 
especially  destined  for  the  entrance  and  exit  of  air,  it  cannot  truth- 
fully be  said  that  satisfactory  ventilation  has  been  secured. 

There  are  several  causes  for  this  state  of  things,  the  most  im- 
portant being  ignorance  of  the  utility  of  fresh  pure  air  for  the 
preservation  and  improvement  of  health,  and  a  consequent  want  of 
demand  for  the  means  of  securing  a  constant  supply  of  this  important 
article.  Perhaps  instead  of  "  ignorance,"  it  would  be  better  to  say 
"want  of  appreciation,"  for  most  people  will  admit  that  ventilation  is 
a  good  and  desirable  thing,  although  it  would  not  occur  to  them  in 
renting  a  house  to  examine  as  to  what  means  of  ventilation  of  the 
living  rooms  are  present  or  available,  nor  would  they  think  of  con- 
sidering the  air  supply  in  selecting  a  school  for  their  children.  The 
evil  effects  qf  the  continuous  inhalation  of  impure  air  are  not  such  in 
most  cases  as  to  attract  the  notice  of  men  unless  the  impurity  is  very 
considerable,  or  the  conditions  of  the  temperature  and  moisture  are 
such  as  to  produce  evident  discomfort  at  the  time.  The  injury 
inflicted  on  the  animal  mechanism  by  breathing  air  deficient  in  oxygen 
and  contaminated  with  animal  exhalations  is  not  perceptible  until 
after  a  considerable  period  of  time,  and  is  then  usually  attributed  to 
other  causes,  and  it  has  only  been  by  careful  and  long  continued  ob- 
servation of  the  effects  of  insufficient  ventilation  upon  bodies  of  men 
subjected  to  it,  and  by  comparison  of  statistics  covering  considerable 
periods  of  time,  that  the  deleterious  results  of  breathing  foul  air  have 
been  demonstrated.  This  proof  has  been  obtained  from  comparing 
the  statistics  of  the  sickness  and  deaths  occurring  during  a  series  of 
years  among  men  in  well  ventilated  and  in  unventilated  barracks,  ships 
and  prisons  ;  among  cavalry  horses  in  well  or  ill  ventilated  stables, 
and  among  monkeys  and  other  wild  animals  when  shut  up  with  a 
defective  air  supply. 


UTILITY    OF    VENTILATION.  19 

The  diseases  which  are  especially  produced  or  aggravated  by 
defective  ventilation  are  those  which  affect  the  respiratory  tract, 
including  chronic  inflammatory  affections  of  the  throat  and  lungs,  and 
especially  phthisis.  With  regard  to  this  last  disease  there  is  abundant 
evidence  that  it  causes  a  much  larger  proportion  of  deaths  among  men 
and  animals  confined  in  ill  ventilated  rooms  and  compelled  to  breath 
air  contaminated  with  organic  products  thrown  off  by  the  lungs  and 
skin,  than  it  does  among  those  living  in  all  other  respects  under  similar 
conditions,  but  having  a  constant  and  abundant  supply  of  fresh  air. 

The  discovery  that  phthisis  is  due  to  the  growth  and  development 
in  the  body  of  a  specific  micro-organism,  the  bacillus  tuberculosis,  does 
not  at  all  invalidate  this  evidence  ;  on  the  contrary  it  strengthens  it ; 
in  part  because  the  probabilities  of  inhaling  the  specific  disease  germ 
are  evidently  greater  where  a  number  of  men  or  animals  are  repeatedly 
breathing  air  contaminated  by  the  dust  of  dried  sputa  or  other  excre- 
tions of  their  companions,  if  any  one  of  these  is  affected  by  the  disease; 
in  part  because  the  inhaling  of  air  loaded  with  dead  or  dying  organic 
matter  produces  changes  in  the  lungs  which  have  apparently  the  effect 
of  diminishing  the  power  of  the  normal  tissues  to  destroy  the  life  of 
disease-producing  organisms  that  may  gain  access  to  them.  From 
evidence  at  hand  we  must  admit  the  existence  of  such  power  on  the 
part  of  normal  tissues  and  its  diminution  in,  or  absence  from  those  that 
are  abnormal.  The  demonstration  by  Cornet  (Zeitschrift  fur  Hygiene, 
1889,  Bd.  V,  s  191)  that  the  dust  of  apartments  occupied  by  tuber- 
culous individuals  frequently  contains  the  bacillus  of  tuberculosis, 
justifies  us  in  assuming  that  in  the  course  of  the  lives  of  many  of  us 
who  are  in  health  and  live  under  proper  sanitary  surroundings,  the 
organism  has  been  inhaled  into  the  lungs,  but  has  been  prevented 
from  playing  its  pathogenic  role  because  of  the  resistance  offered  by 
the  healthy  lung  tissue.  But  in  the  abnormal  tissues  this  vital  resist- 
ance is  diminished,  or,  in  some  cases,  apparently  lost,  and  from 
analogy  we  know  that  this  is  just  the  condition  in  which  all  kinds 
of  infection  most  readily  occur.  It  is  just  this  condition  of  lowered 
vitality  that  is  found  in  the  bodies  of  those  constantly  exposed  to  the 
deleterious  influences  of  the  polluted  air  of  over-crowded,  badly  ven- 
tilated and  otherwise  unsanitary  apartments. 

Statistics  showing  the  excessive  prevalence  of  phthisis  in  ill 
ventilated  rooms  will  be  found  in  the  published  reports  of  the  English, 
French  and  German  armies,  in  the  reports  of  the  English  navy,  and 
in  the  statistical  reports  of  prisons  in  this  country  and  in  Europe  ;  and 
the  intimate  connection  between  an  excessive  death  rate  from  these 


20  UTILITY    OF    VENTILATION. 

affections,  whether  in  man  or  animals,  and  defective  air  supply  is 
now  so  generally  admitted  that  it  is  unnecessary  to  repeat  the  figures 
here.  The  liability  to  spread  by  contagion  or  infection  of  certain 
specific  fevers,  and  notably  of  typhus  fever,  is  greatly  increased  by 
insufficient  ventilation. 

The  desirability  of  provisions  for  ventilation  does  not,  however,, 
depend  upon  its  being  a  means  for  the  prevention  of  consumption, 
or  typhus,  or  other  specific  diseases.  It  comes  under  the  general  head 
of  the  desirability  of  cleanliness.  Most  civilized  men  and  women  are 
unwilling  to  put  on  underclothing  that  has  just  been  taken  off  by 
another  person,  or  to  put  into  their  mouths  articles  of  food  or  drink 
that  have  recently  been  in  other  peoples  mouths,  but  they  take,  with- 
out hesitation,  into  their  lungs  air  that  has  just  come  from  other 
people's  mouths  and  lungs,  or  from  close  contact  with  their  soiled 
clothing  or  bodies. 

"  In  many  cases  it  is  difficult,  or  impossible,  to  separate  the  effects 
of  impure  air  from  those  of  insufficient  or  improper  food,  or  clothing, 
or  from  those  of  occupation  ;  as  for  instance,  in  considering  the 
excessive  mortality  in  tenement  houses  or  in  densely  populated  dis- 
tricts, but  if  we  consider  the  importance  of  respiration  to  life,  the 
immense  surface  which  the  air  passages  and  air  cells  present  for  the 
lodgment  of  particles  brought  into  them  by  the  inspired  air,  and  the 
favorable  conditions  as  regards  moisture  and  temperature  which 
exist  in  them  for  the  growth  and  development  of  micro-organisms, 
provided  these  meet  with  suitable  food  in  the  shape  of  dead  or  non- 
resistant  organic  matter,  we  can  readily  see  that  the  purity  of  the  air 
breathed,  and  the  constant  and  prompt  removal  of  the  excretions 
borne  out  with  it,  must  have  much  to  do.  with  the  health  and  energy  of 
the  individual. 

It  is,  therefore,  well  worth  while  for  every  man  to  understand  that 
abundance  of  fresh  air  is  not  merely  theoretically  a  good  thing  which 
is  to  be  accepted,  if  it  comes  in  his  way,  but  that  it  is  a  necessity  for 
the  preservation  of  health  and  happiness,  and  that  it  is  worth  taking 
special  pains  to  secure.  It  is  also  important  that  those  who  form  and 
direct  public  opinion  on  this  subject — physicians,  architects,  engineers, 
clergymen,  teachers,  school  trustees,  and  legislators,  should  give  more 
attention  to  this  subject  than  most  of  them  have  heretofore  done,  and 
should  look  to  it  that  the  buildings  which  they  plan,  erect  or  manage, 
and  especially  those  in  which  numbers  of  men,  women  or  children  are 
to  be  brought  together,  are  so  constructed  and  arranged  that  no  one 
shall  poison  himself  or  others  by  the  air  which  he  expires. 


21 

I  do  not  mean  by  this  that  every  professional  man  should  aim  to  be 
an  expert  on  plans  and  specifications  for  ventilation,  nor  that  he  should 
rely  on  his  own  judgment  as  to  the  best  way  to  secure  it,  but  that  he 
should  insist  on  having  it  provided  for,  and  should  see  that  skilled  advice 
on  the  subject  is  obtained  for  all  buildings  in  which  he  is  interested. 

The  difficulties  which  architects  and  engineers  find  to  be  most 
prominent  when  they  attempt  to  arrange  a  system  of  ventilation  for  a 
given  building,  mine,  or  other  locality,  are,  first,  the  want  of  a  definite 
generally  recognized  standard  as  to  amount  of  air  required  ;  and 
second,  the  extra  cost  of  construction  and  maintenance  which  is 
involved  in  supplying,  heating,  and  distributing  this  air. 

The  standards  of  satisfactory  ventilation  proposed  by  sanitarians 
are  not  as  yet  accepted  in  engineering  text  books,  the  authors  of 
which  seem  disposed  to  think  that  much  smaller  amounts  of  fresh  air 
than  those  proposed  by  Pettenkofer,  Parkes  and  De  Chaumont,  are 
sufficient.  So  long  as  the  question  as  to  whether  a  given  room  or 
building  is  properly  and  sufficiently  ventilated  is  to  be  decided  by 
opinions  based  on  personal  sensations  only  and  not  upon  the  results 
of  weight  and  measure  of  the  constituents  and  temperature  of  the  air 
which  will  be  independent  of  personal  equations,  so  long  will  it  be 
impossible  to  obtain  an  authoritative  and  reliable  answer.  Upon  the 
standard  for  air  supply  adopted  depends,  to  a  considerable  extent,  the 
expense  of  the  means  required  to  secure  it. 

If  the  question  of  expense  could  be  entirely  set  aside  ventilation 
would  become  a  comparatively  simple  matter,  for  the  resources  of 
modern  engineering  are  ample  to  produce  a  given  standard  of  purity 
of  the  air  in  almost  any  building  that  can  be  constructed  ;  but  to 
secure  good  ventilation  in  cold  climates  during  the  winter  is  expensive 
as  to  the  mode  of  construction  of  the  building  itself,  the  apparatus 
required  for  the  purpose,  and  as  to  its  maintenance  after  the  necessary 
conditions  have  been  provided. 

Among  the  first  questions  which  the  architect  has  to  solve  for 
•each  building  which  he  plans  or  constructs  in  order  to  secure  good 
ventilation  are  the  following — viz.: 

First. — How  much  money  shall  be  allowed  to  secure  ventilation  in 
this  case  ? 

Second. — Which  of  several  methods  should  be  employed  to  effect 
this,  taking  into  consideration  the  character  and  location  of  the  build- 
ing and  the  amount  of  funds  available  ? 

The  answers  to  these  two  problems  will  seldom,  or  never,  be  the 
same  for  any  two  buildings  having  different  owners,  and  this  is  one 


22  UTILITY    OF    VENTILATION. • 

reason  why  it  is  impossible  to  lay  down  simple  and  universal  formulas 
to  secure  satisfactory  heating  and  ventilation  of  a  large  building, 

When  a  gentleman  comes  to  an  architect  for  a  plan  for  a  dwelling 
house,  or  a  board  of  trustees  or  directors  ask  for  plans  for  a  school 
or  a  hospital,  it  is  not  to  be  supposed  that  the  applicants,  while  giving 
general  data  as  to  location,  dimensions  and  proposed  cost,  will  have 
any  definite  ideas  as  to  how  much  of  this  cost  is  to  be  devoted  to  ven- 
tilation. It  is  an  important  part  of  the  business  of  an  architect  to 
decide  this,  and  to  be  careful  from  the  very  beginning  that,  even  in  the 
first  rough  sketch  plans,  as  satisfactory  arrangements  for  ventilation  are 
included  as  the  nature  of  the  case  will  permit.  It  is  also  the  business 
of  the  architect  to  see  that  after  numerous  additions  and  changes 
to  these  sketch  plans  have  been  made  at  the  suggestion  of  various  friends 
and  advisers,  and  the  cost  has  thus  been  increased  above  what  was 
intended,  the  prospective  builder  or  builders  do  not,  in  a  -spasm  of 
economy  and  retrenchment  which  may  attack  them,  make  a  reduction 
in  some  point  which  will  affect  the  ventilation,  rather  than  cut  off  some 
of  the  merely  ornamental  and  comparatively  useless  decorative  work 
of  the  exterior. 

The  connection  of  the  heating  of  a  house  with  its  ventilation  is, 
as  we  shall  show  hereafter,  inseparable ;  nevertheless  many  persons 
will  cheerfully  expend  from  $15,000  to  $20,000  in  building  a  dwelling 
house  for  themselves  in  which  from  $3,000  to  $5,000  shall  be  devoted 
to  ornamental  stone  work  and  cornices,  who  would  not  think  of  spend- 
ing from  $1,000  to  $1,500  for  the  necessary  hot  water  or  low  pressure 
steam  apparatus  to  keep  this  same  house  thoroughly  and  comfortably 
warm  and  well  ventilated.  If,  however,  at  the  very  commencement, 
the  desirability  of  providing  for  constant  ventilation  is  pointed  out  by 
the  architect,  as  he  should  do  in  his  capacity  as  expert  professional 
adviser,  it  will  usually  be  found  that  his  clients  will  accept  his  advice 
just  as  they  will  that  relating  to  the  proper  arrangement  of  the  drains 
and  plumbing  work,  and  by  taking  this  course  the  architect  will  find 
his  clients  much  better  satisfied  with  their  houses  and  with  himself 
than  if  he  defers  to  their  ignorance  in  these  matters.  But,  however 
much  the  architect  may  be  inclined  to  let  the  owners  have  their  own 
way  in  planning  their  own  residences,  when  it  comes  to  public  buildings 
such  as  schools,  hospitals,  etc.,  it  is  his  duty  not  only  to  advise  but  to 
insist  upon  including  proper  arrangements  for  heating,  ventilation, 
drainage  and  plumbing.  If  it  is  his  misfortune  to  have  to  deal  on 
such  matters  with  ignorant  committee  men  who,  with  a  limited  appro- 
priation for  the  purpose,  persist  in  omitting,  for  the  sake  of  cheapness. 


UTILITY    OF    VENTILATION.  23 

some  of  those  points  in  construction  which  are  essential  for  keeping 
the  building  in  proper  sanitary  condition,  it  is  his  duty  as  a  skilled 
professional  man  to  decline  to  have  anything  to  do  with  the  matter 
rather  than  suffer  himself  to  be  used  as  a  tool  to  execute  work  which 
he  knows  will  be  dangerous  to  the  health  and  life  of  his  fellow  citizens, 
or  of  their  children. 

In  most  cold  climates  it  is  impossible  to  have  at  the  same  time 
good  ventilation,  sufficient  heating,  and  cheapness  in  construction 
and  in  the  cost  of  the  fuel  required  during  cold  weather,  to  secure 
comfortable  warmth.  One  reason  why  the  comparative  expensiveness 
of  good  ventilation  is  not  so  well  recognized  in  the  United  States  as  it 
should  be,  is  that  much  of  the  literature  on  the  subject  has  heretofore 
been  furnished  by  English  authors  who  write  with  reference  to  the 
climate  of  England.  This  climate  is  very  different  from  our  own, 
being  much  more  uniform,  and  having  a  much  higher  average  propor- 
tion of  moisture  in  the  air,  which  permits  of  the  use  of  lower  temper- 
atures in  warming  than  are  acceptable  here.  In  the  United  States 
rooms  must  be  kept  at  a  temperature  of  from  68°  to  70°  F.,  tcr  insure 
the  comfort  of  the  occupants  and  to  prevent  complaints,  while  in 
England  60°  F.,  seems  to  be  the  recognized  standard. 

Open  fireplaces  and  grates  can  therefore  be  used  there  more  ex- 
tensively than  here,  and  in  arranging  apparatus  for  heating  by  indirect 
radiation,  it  is  necessary  to  provide  more  heating  surface  than  is  called 
for  by  the  specifications  of  English  engineers.  This  is  a  fact  which 
must  be  constantly  borne  in  mind  in  reading  the  books  of  Edwards, 
Hood,  or  other  English  writers  on  this  subject,  and  it  will  be  found 
well  presented  and  strongly  insisted  on  in  a  paper  by  Mr.  Robert  Briggs, 
in  the  January  and  February  numbers  of  the  Journal  of  the  Franklin 
Institute  for  1878,  entitled,  "On  the  Relation  of -Moisture  in  the  Air  to 
Health  and  Comfort." 

How  may  we  define  "good  ventilation,"  or  know  whether  it  has 
been  secured  in  any  given  building?  In  the  great  majority  of  cases 
it  includes  the  idea  of  a  thorough  mixing  of  pure  air  with  impure  air, 
in  order  that  the  latter  may  be  diluted  to  a  certain  standard. 

Perfect  ventilation  can  be  said  to  have  been  secured  in  an  inhabited 
room  only  when  any  and  every  person  in  that  room  takes  into  his  lungs 
at  each  respiration  air  of  the  same  composition  as  that  surrounding  the 
building,  and  no  part  of  which  has  recently  been  in  |jis  own  lungs  or  of 
those  of  his  neighbors,  or  which  consists  of  products  of  combustion 
generated  in  the  building,  while  at  the  same  time  he  feels  no  currents 
or  draughts  of  air,  and  is  perfectly  comfortable  as'regards  temperature, 


24  UTILITY    OF    VENTILATION. 

being  neither  too  hot  nor  too  cold.  Very  rarely,  indeed,  can  such  perfect 
ventilation1  be  secured  if  the  number  of  persons  in  the  room  exceeds 
two  or  three  ;  in  fact,  few  attempts  have  been  made  in  this  direction. 
One  of  these  was  in  the  house  of  the  late  Mr.  Thomas  Winans,  of 
Baltimore,  where  the  floors  were  perforated  uniformly  all  over  the 
room,  as  was  done  by  Dr.  Reid  for  the  British  House  of  Commons, 
thus  making  the  floor  a  gigantic  register  or  grating  through  which  the 
fresh  incoming  air,  having  been  previously  warmed  and  moistened  in 
mixing  chambers  below,  is  to  stream  steadily  upward  at  a  uniform 
velocity  sufficient  to  remove  all  the  products  of  respiration  or  of  com- 
bustion as  rapidly  as  formed.  It  requires  even  more  than  this  to  secure 
the  perfect  comfort  as  regards  temperature  above  alluded  to,  but  this 
will  be  explained  when  we  come  to  speak  of  the  heating  and  ventila- 
tion of  large  assembly  halls.  The  amount  of  air  required  to  secure 
this  perfect  ventilation  is  very  great.  Take,  for  instance,  a  room 
12  feet  square,  and  suppose  that  the  air  in  it  is  to  move  uniformly 
upward  at  trie  rate  of  6  inches  per  second.  This  is  equivalent  to  an 
air  supply  of  72  feet  per  second.  Theoretically,  it  is  true  that,  if  the 
air  moves  regularly  and  steadily  upward  at  all  points  in  the  room  at 
the  rate  of  even  i  inch  per  second  it  might  be  sufficient — but  prac- 
tically, at  least  six  times  this  velocity  is  required  to  overcome  dis- 
turbances caused  by  opening  doors,  the  movement  of  persons,  etc. 

Probably  this  statement  of  air  supply  required  gives  no  definite 
idea  as  to  its  cost,  and  it  may  be  more  fully  understood  by  con- 
sidering'that  it  would  require  at  least  thirty  times  as  much  coal 
to  heat  a  room  thus  supplied  as  would  be  used  for  heating  a  room 
of  the  same  size  having  only  the  ordinary  heating  and  ventilating 
arrangements. 

What  would  be  considered  by  all  sanitarians  as  good  ventilation 
would  not  require  nearly  so  much  air  as  this.  Good,  ordinary  ventila- 
tion is  presumed  to  be  secured  by  keeping  the  vitiated  air  constantly 
diluted  to  a  certain  standard.  It  does  not  attempt  to  maintain  in  a 
building  or  room  air  as  pure  as  that  outside,  but  only  air  which  shall 
contain  but  a  certain  proportion  of  impurity — for  all  the  air  with  which 
our  ventilating  appliances  are  to  deal  will  contain  impurities.  Some 
of  these  impurities  are  more  dangerous  than  others,  and  are  less 
affected  by  this  process  of  dilution.  Offensive  or  poisonous  gases  of 
ail  kinds,  "such  as  sulphuretted  hydrogen  or  carbonic  oxide,  can  be 
diluted  by  fresh  air,  just  as  solutions  of  arsenic  or  strychnine  can  be 
by  pure  water,  until  a  mouthful  of  such  diluted  air  or  fluid  is  neither 
specially  hurtful  or  unpleasant. 


UTILITY    OF    VENTILATION.  25 

The  most  dangerous  impurity  in  some  air,  such  as  that  contained 
in  a  hospital  ward  for  contagious  diseases,  is  often  not  gaseous,  has  no 
very  marked  or  unpleasant  odor,  and  cannot  be  detected  by  ordinary 
means  of  chemical  analysis.  It  consists  of  minute  living  organisms 
which  have  the  power  of  producing  disease  when  they  gain  access  to 
the  human  body  under  favorable  circumstances.  Many  of  these  organ- 
isms, known  as  bacteria,  have  been  proven  to  be  the  cause  of  certain 
specific  inflammations  and  other  diseases.  The  process  of  diluting  by 
ventilation  the  air  of  a  room  which  contains  them  does  not  dilute  the 
individual  bacterium  or  spore,  and  its  effect  in  removing  them  from  the 
apartment  is  much  less  than  its  effect  upon  diffused  gases  or  vapors. 
Most  of  them  are  of  greater  specific  gravity  than  the  air,  especially 
when  adhering  to  particles  of  dust,  and  hence  their  tendency  is  to 
remain  wherever  dust  can  settle,  and  to  be  diffused  by  whatever  causes 
the  diffusion  of  dust  in  the  air,  such  as  sweeping,  dusting,  movements 
of  persons,  or  strong  air  currents. 

It  is,  therefore,  evident  that  the  prevention  of  the  entrance  of 
the  dangerous  forms  of  micro-organisms  into  a  building  where  it  is 
possible  to  do  so  is  a  matter  of  special  importance,  since  it  is  very 
difficult  to  dispose  of  them  by  ventilation  alone  when  they  have  once 
gained  entrance,  and  hence  ventilation  is  no  efficient  substitute  for 
proper  plumbing,  and  the  avoidance  of  collections  of  decaying  organic 
matter  within  the  house. 

In  the  great  majority  of  buildings  the  ventilation  may  be  planned 
and  arranged  with  reference  only  to  the  ordinary  impurities  of  air  in 
inhabited  rooms,  and  to  the  maintenance  of  an  agreeable  temperature. 

It  should  be  remembered,  also,  that  even  in  the  northern  part  of 
the  United  States  and  in  Canada,  little  or  no  heat  is  required  for  over 
half  of  the  year,  and  that  buildings  can  be  planned  so  as  to  secure 
good  ventilation  during  the  warmer  months  with  little  or  no  extra 
expense,  provided  that  the  matter  has  been  duly  considered  in  the 
beginning,  and  not  taken  up  as  an  afterthought  when  nearly  every 
detail  of  construction  has  been  decided  upon. 


CHAPTER    II. 

HISTORY    AND    LITERATURE    OF    VENTILATION. 

THE  necessity  which  exists  in  certain  mines  for  arrangements  to 
ensure  a  sufficient  supply  of  fresh  air  in  the  deeper  shafts  and 
galleries  to  dilute  and  expel  the  gases  which  would  otherwise  accumu- 
late and  form  explosive  mixtures,  or  interfere  with  respiration  and 
make  dim  or  extinguish  the  miners'  lamps,  was  probably  what  first 
gave  rise  to  plans  for  ventilation  without  regard  to  either  heating  or  to 
cooling  buildings  by  means  of  air  currents. 

The  earliest  description  of  apparatus  or  special  methods  employed 
for  this  purpose  is  given  in  the  treatise  of  George  Agricola,  published 
in  1546,  and  entitled  "  De  re  metallica,"  in  which  the  methods  used  in 
the  mines  of  Bohemia  and  Saxony  are  briefly  indicated.  These 
included  the  use  of  fire  to  create  an  upward  current  in  certain  shafts  ; 
of  a  sort  of  large  bellows  with  which  air  could  be  pumped  into  spe- 
cially foul  and  dangerous  pits  or  tunnels,  and  of  rotating  fan  wheels 
to  ensure  a  current  in  an  horizontal  gallery. 

Long  before  this  date,  physicians  had  observed  and  commented 
upon  the  need  for  the  renewal  of  air  to  support  healthy  human  /life, 
and  had  especially  directed  that  this  should  be  secured  in  the  room  of 
a  sick  person  by  means  of  perflation,  or,  as  Celsus  suggests,  b^  the  use 
of  a  small  fire  ;  and  the  use  of  wind  conductors  or  mulgiifs,  as  they  are 
called  in  Egypt,  to  secure  cold  currents  of  air  throughout  the  house 
for  the  sake  of  coolness,  is  of  very  ancient  date. 

Special  openings  in  the  ceilings  or  roofs  were  provided  in  the 
ancient  Roman  Baths  for  the  purpose  of  giving  exit  to  hot  air  and  thus 
regulating  the  temperature,  and  in  the  Hall  of  the  Baths  of  the  Alham- 
bra  at  Granada,  constructed  in  the  thirteenth  century,  short,  funnel- 
shaped,  glazed  tubes  are  inserted  in  the  roof  for  purposes  of  ventila- 
tion. 

Practically,  however,  the  history  of  ventilation  begins  with  the 
attempts  at  ventilating  the  Houses  of  Parliament  in  Lonaon  in  1660 
by  the  architect,  Sir  Christopher  Wren  ;  and  it  has  been  truly  said  that, 
as  almost  every  device  has  been  tried  in  these  halls  at  one  time  or 


HISTORY    AND    LITERATURE.  27 

other,  the  history  of  these  attempts  would  be  almost  equivalent  to  a 
history  of  the  art  of  ventilation  in  its  entirety.  Sir  Christopher's  plan 
was  to  cut  a  large  square  hole  in  each  corner  of  the  ceiling  of  the 
House,  over  each  of  which  holes  he  placed  a  short  funnel-shaped  tube 
leading  into  the  room  above,  which  funnels  could  be  opened  and  closed 
by  means  of  valves.  As  there  were  apparently  no  special  provisions 
for  fresh  air  supply,  this  scheme  produced  a  sort  of  circulation,  bring- 
ing down  the  cold  air  from  beneath  the  roof,  and  giving  rise  to  great 
complaints  of  draughts.  This  led  to  the  calling  upon  Dr.  J.  T. 
Desaguliers  to  remedy  the  difficulties,  and  thus  induced  this  distin- 
guished physicist  and  mechanician  to  devote  special  study  to  the 
mechanical  problems  connected  with  ventilation. 

Dr.  Desaguliers  was  of  French  origin,  having  been  born  in  New 
Rochelle  in  1683,  and  taken  by  his  father  to  England  on  the  revoca- 
tion of  the  Edict  of  Nantes  in  1685.  He  became  a  lecturer  on  experi- 
mental philosophy  in  Oxford  in  1710,  and  in  1714  was  made  a  Fellow 
of  the  Royal  Society,  to  which  he  presented  a  number  of  communica- 
tions in  succeeding  years,  and  is  well  known  by  his  "Course  of  Experi- 
mental Philosophy,"  which  passed,  through  several  editions,  and  in 
which  he  gives  a  modest  and  rather  humorous  account  of  his  adven- 
tures in  trying  to  improve  the  ventilation  of  the  House. 

The  physics  of  air  and  the  effects  of  heat  were  an  essential  part 
of  his  course  of  instruction;  but  he  had  been  led  to  give  special  atten- 
tion to  the  heating  and  ventilation  of  houses  by  a  little  book  by  one 
N.  G.,  published  in  Paris  in  1713,  and  entitled,  "  La  Mechanique  du 
Feu."  In  a  subsequent  edition  the  author  gave  his  name  in  full  as 
Nicholas  Gauger.  In  a  work  entitled,  "On  the  History  and  Art  of 
Warming  and  Ventilating  Buildings  .  .  .  by  Walter  Bernan,"  pub- 
lished in  two  volumes  in  London  in  1845,  the  authorship  of  this  work 
by  N.  G.  is  attributed  to  the  celebrated  Cardinal  de  Polignac,  and  this 
statement  has  been  accepted  by  many  subsequent  writers.  It  may  be 
noted,  by  the  way,  that  the  name  "  Walter  Bernan  "  appears  to  have 
been  merely  a  nom  de  plume,  and  that  the  book — which  is  a  valuable 
one  for  reference — was  really  written  by  Mr.  Robert  Meikleham,  C.  E. 
(See  Edwards  [F.]  on  the  Ventilation  of  Dwelling  Houses,  etc.,  8vo., 
Lond.,  1868,  p.  2.) 

Nicholas  Gauger  was,  however,  a  very  real  personage,  and,  as  Mr. 
Charles  Tomlinson  has  pointed  out,  was  really  the  author  of  the  book 
attributed  to  him.  He  was  a  student  of  experimental  philosophy,  and 
his  book  is  a  remarkable  one,  containing,  as  it  does,  descriptions  of  the 
true  principles  of  some  of  the  best  of  modern  fireplaces,  especially 


28  HISTORY    AND    LITERATURE. 

those  which  are  designed  to  introduce  fresh  warm  air  into  the  room 
which  is  to  be  heated.  Dr.  Desaguliers  translated  this  work  into 
English,  and  published  it  in  London  in  1715,  under  the  title  of  "Fires 
Improved;  or,  A  New  Method  of  Building  Chimnies  so  as  to  Prevent 
Their  Smoking,  in  Which  a  Small  Fire  Shall  Warm  a  Room  Much 
Better  than  a  Large  One  Made  the  Common  Way."  A  second  edition 
of  this  translation,  with  an  appendix,  was  published  in  1736. 

The  ideas  contained  in  Ganger's  treatise  were  not  all  original  with 
him,  for  the  rules  for  properly  proportioning  the  dimensions  of  a 
fireplace  and  of  its  chimney  to  prevent  smoking  had  been  stated  by  a 
French  architect  and  physician,  M.  Louis  Savot,  so  early  as  1624;  but 
Gauger  treats  his  subject  from  a  scientific  as  well  as  a  practical  point 
of  view,  describing  experiments  to  prove  that  air  is  heated,  not  by 
radiation  but  by  contact  with  warm  surfaces;  that  warm  air  rises 
above  that  which  is  cooler,  and  that  currents  may  thus  be  produced; 
and  then  proceeds  to  describe  and  figure  fireplaces  and  grates  intended 
to  heat  an  incoming  current  of  air,  by  which  means,  he  says,  "You 
may  be  able  to  kindle  a  fire  speedily,  to  warm  yourself  at  the  game 
time  on  all  sides  without  scorching/ to  breathe  a  pure  air  always  fresh, 
to  be  never  annoyed  with  smoke  in  one's  apartment,  nor  have  any 
moisture  therein."  He  points  out  that  the  horizontal  section  of  the 
fireplace  should  be  on  the  lines  of  the  parabola,  in  order  that  the 
greatest  number  of  rays  of  heat  may  be  reflected  out  into  the  room; 
provides  for  the  heating  of  air  by  conduction  from  the  back,  and  states 
that  by  the  fireplace  air  may  be  either  admitted  from  the  room  itself  or 
from  the  outside;  and  describes  a  form  of  paper  pendulum  to  be  used 
to  show  the  relative  velocity  of  the  incoming  air  in  order  to  determine 
the  amount  of  air  which  is  admitted,  his  estimate  being  that  the  con- 
tents of  a  room  of  2,000  cubic  feet  should  be  changed  in  about  a 
quarter  of  an  hour.  He  says:  "There  is  indeed  an  inconveniency, 
which  is,  that  warm  air  entering  continually  will  at  last  make  the  room 
too  hot;  but  this  is  easily  remedied  by  stopping  up  the  hole  where  the 
hot  air  comes  in.  But  then,  as  there  would  no  longer  be  a  circulation 
of  fresh  air,  it  is  better  to  have  a  direct  communication  with  the  exter- 
nal air  near  the  place  where  it  comes  out  after  it  is  heated  in  the  hol- 
lows. Thus  you  may  sometimes  have  hot,  and  sometimes  cold,  and 
sometimes  temperate  air,  in  what  proportion  you  please,  by  opening 
sometimes  one  hole,  sometimes  the  other,  and  sometimes  both."  And 
again:  "To  be  soon  and  agreeably  warmed  by  external  air  brought 
into  a  room  after  the  above  mentioned  manner  is  not  the  only  or  the 
greatest  advantage  reaped  by  our  new  invention,  for  as  well  the  incon- 


HISTORY    AND    LITERATURE.  29 

veniences  of  a  great  fire  as  that  of  extreme  cold  are  removed.  The 
larger  particles  of  the  fuel  darted  out  against  us,  when  we  have  too 
large  a  fire,  or  when  we  are  too  near  the  chimney,  burn  and  dry  up  the 
lungs,  and  ruin  the  eyes,  as  may  be  perceived  by  their  pain  and  red- 
ness; spoil  the  delicate  skin  of  the  ladies,  hurt  the  eyelids  and  destroy 
the  finest  complexions;  all  which  evils  are  prevented  by  the  use  of  the 
new  chimneys.  As  for  sick  people,  they  may  be  looked  upon  as  abso- 
lutely necessary;  for  the  corrupted  breath  of  patients,  the  ill  humors 
which  go  out  of  their  bodies  by  transpiration,  particles  from  their 
physick,  and  their  excrements  mixing  with  the  air  that  continues 
always  the  same  (because  we  dare  not  in  cold  weather  open  any  place 
to  let  in  fresh  air)  vitiate  the  air  more  and  more;  and  the  patient  has 
the  infection  of  the  air  to  struggle  with,  as  well  as  his  distemper; 
which  often  occasions  the  death  of  those  that  are  sick,  and  sometimes 
that  of  such  as  visit  them  pretty  much.  Now  if  fresh  air  from  the 
hollows  of  the  chimney  be  let  into  the  sick  man's  room,  of  what  degree 
of  heat  is  thought  most  proper,  it  will  drive  out  the  corrupted  air,  and 
so  take  off  all  the  inconveniences  which  must  necessarily  be  occa- 
sioned by  air  impregnated  with  too  many  poisonous  particles.  Be- 
sides, since  we  can  give  the  patient  what  degree  of  warmth  we  please, 
there  will  be  no  need  of  loading  and  choking  him  up  with  blankets 
after  the  usual  manner.  .  .  .  It  is  a  mistake  in  those  who  would 
be  affected  with  the  same  degree  of  heat  to  have  their  room  just  so  hot 
as  to  keep  the  thermometer  at  the  same  degree;  because  they  shall  be 
differently  affected,  according  to  the  greater  or  less  natural  heat  of 
their  bodies  at  that  time." 

When  in  1723  Dr.  Desaguliers  was  requested  to  improve  the  ven- 
tilation of  the  House  of  Commons,  his  first  scheme  was  to  retain  Sir 
Christopher  Wren's  holes  and  pyramids,  but  to  carry  tubes  from  these 
to  chimneys,  and  to  heat  the  tubes  by  means  of  fires.  When  these 
fires  were  lighted  early,  so  that  the  tubes  and  chimneys  were  thoroughly 
heated  before  the  House  was  in  session,  the  upward  currents  were 
maintained;  but  the  housekeeper,  Mrs.  Smith,  disapproved  of  the 
new  plan,  which  interfered  with  her  rooms,  and  she  prevented  it  from 
working  by  forgetting  to  light  the  accelerating  fires  until  the  House 
was  crowded  and  hot. 

The  doctor  then  turned  his  attention  to  mechanical  means  for 
drawing  out  foul  or  forcing  in  fresh  air,  including  several  kinds  of 
pumps  and  blowing  wheels  or  fans,  one  of  which  last  he  arranged  for 
the  House  of  Commons  in  1736.  The  plan  of  this  wheel  is  shown  in 
Fig.  i  and  Fig.  2,  copied  from  Meikleham's  work  above  referred  to. 


30  HISTORY    AND    LITERATURE. 

The  wheel  shown  in  Fig.  i  and  Fig.  2  is  described  to  be  7  feet  in 
diameter  and  i  foot  wide.  The  12  radiating  partitions  a  a,  approached 
to  within  9  inches  of  the  axis,  leaving  a  circular  opening  z,  18  inches 
in  diameter.  The  wheel  was  inclosed  in  a  concentric  case  /,  which 
had  a  "  blowing  pipe  "  ;;/,  on  the  upper  part  of  its  circumference,  and 
a  suction  pipe  n,  that  communicated  by  a  funnel  d,  with  the  central 
opening  z,  in  the  wheel,  which  was  turned  by  a  handle  <?,  attached  to 
the  axis  c,  that  went  through  the  case  and  rested  on  a  standard.  The 
"fanner"  was  adjusted  to  revolve  easily,  but  as  closely  to  its  concen- 
tric casing  /,  as  possible,  and  it  had  no  communication  with  the  air 
except  through  the  suction  and  blowing  pipes.  By  the  revolution  of 
the  wheel,  the  air  entering  through  the  central  opening  into  the  spaces 


FIG.  i. 


FIG.  2. 


r  ;-,  formed  by  the  radiating  partitions,  was  thrown  by  the  centrifugal 
motion  towards  the  circumference,  where  it  was  confined  by  the  con- 
centric casing,  and  carried  round  until  it  arrived  at  the  opening  of  the 
blowing  pipe  m,  into  which  it  was  impelled  by  each  radiating  partition 
in  continuous  revolution.  When  the  suction  pipe  «,  was  open  to  the 
atmosphere  or  to  a  space  containing  heated  air,  and  the  blowing  pipe 
connected  with  a  room,  the  apartment  was  filled  with  cold  or  with 
heated  air,  in  any  desired  quantity,  by  increasing  or  diminishing  the 
speed  of  the  wheel.  If  foul  air  had  to  be  drawn  out,  the  suction  pipe 
was  connected  with  the  room  and  the  blowing  pipe  with  the  atmos- 
phere ;  and  when  it  was  not  required  either  to  draw  out  foul  or  intro- 
duce fresh  air,  but  to  keep  the  air  of  the  room  in  motion  only,  the 


HISTORY    AND    LITERATURE.  31 

suction  and  blowing  pipe  both  opened  into  the  apartment.  This  con- 
trivance, with  some  minor  changes,  appears  to  have  remained  in  use 
for  80  years. 

At  the  request  of  the  Lords  of  the  Admiralty,  he  then  undertook 
to  make  a  similar  wheel  to  be  tried  on  one  of  the  ships  of  the  Royal 
Navy,  attention  having  been  attracted  to  the  foul  and  offensive  condi- 
tion of  these  ships,  and  to  the  great  prevalence  of  infectious  fever 
among  the  soldiers  embarked  on  them.  At  that  time  the  windsail  was 
the  only  means  of  securing  fresh  air  in  the  hold  of  a  ship,  and  in  calm 
weather  this  was,  of  course,  useless.  But  the  Surveyor  of  the  Navy, 
Sir  Jacob  Ackworth,  who  was  directed  to  report  on  Desaguliers'  ma- 
chine, did  not  believe  in  such  new-fangled  contrivances,  and,  having 
arranged  a  time  for  the  experiment  when  there  was  plenty  of  wind, 
demanded  a  trial  of  the  machine  against  his  tavonte  windsails.  As 
the  wheel  was  a  very  small  one,  with  pipes  only  3  by  5  inches,  while 
the  tube  of  the  windsail  was  between  2  and  3  feet  in  diameter, 
this  contest  was,  of  course,  declined.  Sir  Jacob  told  the  engineer  that 
he  was  sorry  the  doctor's  wheel  succeeded  no  better,  for  he  thought 
it  might  be  a  very  pretty  thing  in  a  house;  and  the  doctor  says:  "Now, 
let  every  impartial  person  judge  whether  I  have  not  reason  to  complain, 
for  not  one  of  the  Lords  of  the  Admiralty,  who  talked  of  having  many 
of  these  ventilators  made  for  the  preservation  of  the  health  of  the  per- 
sons then  going  to  Jamaica,  condescended  to  witness  the  experiment, 
and  Sir  Jacob,  who  condemned  the  thing,  would  not  once  be  present 
to  observe  its  operation;  and  thus  ended  my  scheme,  which  I  hoped 
would  have  been  of  great  benefit  to  the  public." 

About  this  time  the  Rev.  Stephen  Hales,  perpetual  curate  of  Ted- 
dington  and  rector  of  Faringdon,  became  a  frequent  contributor  to  the 
Philosophical  Transactions,  and  had  much  to  say  on  the  subject  of  ven- 
tilation. He  declared  that  if  the  immoderate  use  of  spirituous  liquors 
was  less  general,  and  the  benefits  of  ventilation  more  generally  known 
and  experienced,  mankind  would  surely  become  better  and  happier. 
In  1758  he  published  a  treatise  on  ventilators  in  two  parts,  forming  a 
volume  of  over  400  pages,  octavo.  This  was  largely  concerned  with 
the  ventilation  of  ships  by  the  use  of  inject  and  exhaust  pumps,  which 
were  arranged  somewhat  on  the  principle  of  the  blacksmith's  bellows. 
These  bellows  were  sometimes  very  large,  being  10  feet  long,  and 
were  arranged  so  that  certain  chambers  might  be  ventilated  at  one  time 
and  certain  others  at  another.  He  first  applied  the  machine  to  the 
County  Hospital  and  County  Jail  at  Winchester;  afterwards  to  the 
Savoy  Prison,  and  subsequently  to  Newgate.  The  great  practical 


32  HISTORY    AND    LITERATURE. 

• 

objection  to  the  ventilating  bellows  of  Dr.  Hales,  and  to  the  ventilat- 
ing wheel  of  Dr.  Desaguliers,  was  the  necessity  of  working  them  by 
manual  labor,  although  in  certain  vessels  there  appears  to  have  been 
no  objection  of  this  kind.  In  a  letter  from  Captain  Ellis,  published  in 
the  Philosophical  Transactions,  Vol.  XLVII.,  1750-51,  he  states  that 
"  the  bellows  were  far  from  inconvenient,  and  afforded  good  exercise 
for  the  slaves,  and  a  means  of  preserving  the  cargo  and  lives."  This 
treatise  on  ventilators  was  translated  into  French  by  a  French  phy- 
sician.. There  does  not  seem  to  have  been  the  best  of  feeling  existing 
between  Dr.  Desaguliers  and  Dr.  Hales.  The  latter,  in  his  first  an- 
nouncements, makes  no  mention  of  his  predecessor's  contrivance, 
although  one  of  the  wheels  had  been  furnished  him;  and  in  his  book 
on  ventilators,  in  1758,  he  refers  to  the  blowing  wheel  of  the  House  of 
Commons  disparagingly  as  being  not  specially  new,  and  not  as  satis- 
factory as  his  own  arrangement.  He,  however,  in  his  turn  was  dis- 
paraged by  another  rival  ventilator,  Mr.  Samuel  Sutton,  a  brewer,  who, 
in  the  year  1739,  learning  that  the  sailors  on  board  the  fleet  were  so 
dangerously  ill  for  want  of  fresh  air  that  they  were  put  ashore  to  recover 
their  health,  and  that  the  ships  stunk  to  such  a  degree  that  they  infected 
one  another,  undertook  to  do  all  that  was  possible  for  their  relief,  and 
for  this  purpose  he  proposed  to  withdraw  the  foul  air  out  of  the  ships 
by  means  of  pipes  connected  with  the  kitchen  or  galley  fire,  instead  of 
using  mechanical  ventilators.  He  shut  off  the  ordinary  supply  of  air 
to  the  fire,  and  led  tubes  from  the  ship's  hold  to  the  ash  pit  below  the 
fire.  He  obtained  a  patent  for  this  arrangement,  and  then  proceeded 
to  visit  Sir  Jacob  Ackworth-,  the  same  naval  officer  v/ho  had  dealt  with 
Dr.  Desaguliers.  Sir  Jacob  made  an  appointment  for  Mr.  Sutton  to 
call  upon  him  at  a  future  day,  and  then  allowed  him  to  wait  about  until 
evening,  after  which  he  saw  him,  and  after  a  little  conversation  told  him 
that  no  experiment  should  be  made  if  he  could  hinder  it.  Mr.  Sutton, 
however,  was  a  business  man,  and  had  some  influence  at  court  and  no 
scruples  about  using  it,  so  that  he  succeeded  in  getting  an  order  from 
the  Admiralty  to  have  his  contrivance  tested;  but  it  was  only  through 
the  influence  of  Dr.  Mead,  Physician  to  His  Majesty  and  the  President 
of  the  Royal  Society,  that  a  trial  was  actually  made.  Mr.  Sutton's 
pamphlet,  entitled,  uAn  Historical  Account  of  a  New  Method  for 
Extracting  the  Foul  Air  Out  of  Ships,"  of  which  a  second  edition  was 
published  in  London  in  1749,  is  very  entertaining  reading,  but  con- 
tributes nothing  to  the  practical  knowledge  of  methods. 

The  improvements  in  heating  apparatus,  fireplaces,  etc.,  made  by 
Franklin,  Rumford  and  others,  brought  with  them  some  additional 


HISTORY    AND    LITERATURE.  ,  33 

arrangements  for  air  supply;  but  very  little  was  done  in  the  way  of 
ventilation,  and  the  Houses  of  Parliament  remained  substantially  in 
the  same  condition  until  the  year  1811,  when  Sir  Humphrey  Davy 
undertook  to  improve  the  warming  and  ventilation  of  the  House  of 
Lords.  His  plan  was  to  admit  the  fresh  warm  air  through  a  large 
number  of  holes  in  the  floor,  and  to  withdraw  the  foul  air  at  the  ceiling 
through  two  apertures  covered  with  open  wire  work,  from  which  metal 
tubes  were  carried  to  the  external  air,  and  when  extra  ventilation  was 
required  these  tubes  were  heated  to  accelerate  the  velocity  of  the  air 
passing  through  them.  He  seems  to  have  badly  calculated  the  diameter 
of  the  tubes  necessary  to  carry  off  the  air;  each  of  which  was  only  i 
foot  square,  so  that  his  plan  became  a  total  failure.  The  exact  num- 
ber of  the  perforations  in  the  floor,  as  well  as  the  fee  received,  is 
recorded  in  two  lines  of  an  epigram  given  by  Meikleham: 

"  For  boring  20,000  holes, 
The  Lords  gave  nothing — d n  their  souls." 

The  horizontal  heating  flues  beneath  the  floor  were  14  inches 
wide,  1 8  inches  deep,  and  nearly  100  feet  long.  These  gradually 
cracked,  and  permitted  some  of  the  furnace  gases  to  escape  into  the 
hall;  and  finally,  in  1834,  when  a  large  quantity  of  waste  paper  was 
burned,  the  woodwork  in  the  vicinity  took  fire,  and  both  Houses  Of 
Parliament  were  destroyed. 

The  next  to  try  his  hand  at  improving  the  ventilation  of  the 
House  of  Commons  was  the  Marquis  de  Chabannes,  who  used  steam, 
both  for  warming  the  air  to  be  introduced  "and  for  heating  accelerating 
coils  placed  in  the  exhaust  ducts  above  the  ceilings,  having  previously 
tried  a  somewhat  similar  system  at  Covent  Garden  Theatre.  The 
single  main  foul  air  shaft  rising  perpendicularly  from  above  the  ceiling 
of  the  hall  of  the  House,  had  branches  from  openings  in  different  parts 
of  the  ceiling,  was  heated  by  steam  cylinders  placed  near  its  base  and 
terminated  above  the  roof  in  a  cowl  4  feet  in  diameter. 

The  use  of  steam  for  heating  and  ventilating  was  especially  urged 
by  Mr.  Thomas  Tredgold,  an  English  engineer,  who  published  in  1824 
a  treatise  entitled,  "  Principles  of  Warming  and  Ventilating  Public 
Buildings,  Dwelling-houses,  etc."  This  went  through  three  editions, 
and  was  a  standard  authority  on  the  subject — in  fact,  his  formulae  for 
proportioning  supply  of  air-heating  surface,  etc.,  are  still  in  use  among 
certain  heating  engineers. 

As  the  result  of  calculations  as  to  the  various  causes  of  impurity 
of  air  produced  by  respiration,  perspiration,  etc.,  he  concluded  that 


34  HISTORY    AND    LITERATURE. 

each  person  should  be  allowed  4  cubic  feet  of  fresh  air  per  minute— 
or  less  than  one-tenth  the  amount  actually  required — and  this  error 
has  been  copied  in  a  number  of  later  works. 

Taking  this  as  a  basis  he  goes  on  to  give  his  working  formulae  as 
follows  : 

"  The  most  difficult  season  for  ventilation  is  the  summer  ;  and  we 
may  consider  that  there  should  not,  in  warm  weather,  be  a  difference 
of  temperature  exceeding  10  degrees;  and  with  this  limit  as  to  varia- 
tion of  temperature,  we  shall  have  this  rule  for  the  area  of  the  tubes. 

"  Rule. — Multiply  the  number  of  people  the  room  is  to  contain  by 
4,  and  divide  this  product  by  43  times  the  square  root  of  the  height  of 
the  tubes  in  feet,  and  the  quotient  is  the  area  of  the  ventilator  tube  or 
tubes  in  feet."  Again, 

"Rule. — In  public  buildings,  dwelling  houses,  etc.,  the  quantity 
of  air  in  cubic  feet  to  be  warmed  in  one  minute  should  be  equivalent 
to  four  times  the  number  of  people  the  room  is  intended  to  contain, 
added  to  eleven  times  the  number  of  external  windows  and  doors, 
added  to  one  and  a  half  times  the  area  in  feet  of  the  glass  exposed 
to  the  external  air."  This  number  of  cubic  feet  of  air  to  be  heated 
is,  by  another  rule,  "  to  be  multiplied  by  the  difference  between  the 
temperature  the  room  is  to  be  kept  at,  and  that  of  the  external  air,  in 
degrees  of  Fahrenheit's  thermometer,  and  divide  the  product  by  2.1 
times  the  difference  between  200  and  the  temperature  of  the  room;  this 
quotient  will  give  the  quantity  of  surface  of  cast-iron  steam  pipe  that 
will  be  sufficient  to  maintain  the  room  at  the  required  temperature." 

"  If  the  cubic  feet  of  space  in  a  room  be  divided  by  the  quantity 
of  air  to  be  warmed  in  one  minute  to  sustain  its  temperature,  the  quo- 
tient will  be  nearly  the  number  of  minutes  it  will  require  to  raise  it  to 
a  given  temperature,  the  ventilation  being  stopped  during  the  time." 

These  examples  are  sufficient  to  indicate  why  the  work  of  Tredgold 
has  continued  to  enjoy  so  great  an  authority  among  those  engaged  in 
the  business  of  heating  and  ventilating.  Its  precepts  are  positive  and 
definite.  There  are  no  exceptions.  It  is  assumed  that  the  con- 
struction of  all  buildings  is  alike  and  of  the  beet  character,  and  that 
the  temperature  of  the  external  air  varies  only  between  comparatively 
close  limits, — in  fact,  those  of  the  English  climate — and  that  any  amount 
of  foulness  of  air  which  can  be  endured  is  not  unhealthy.  The  formulae 
of  Tredgold,  as  has  been  stated,  appear  slightly  modified  in  many 
engineering  manuals,  French,  German,  English  and  American,  although 
their  source  is  by  no  means  always  acknowledged.  We  shall  have 
occasion  to  comment  upon  the  fundamental  principles  of  his  formulae 


HISTORY    AND    LITERATURE.  35 

in  speaking  of  the  quantity  of  air   to   be    supplied   and  of   heating 
surface  to  be  provided. 

In  1838,  Dr.  Neil  Arnott  published  a  little  book  on  warming  and 
ventilating,  which  was  devoted  chiefly  to  the  description,  and  advocacy 
of  the  use,  of  his  self-regulating  stove.  As  he  assumed  that  from 
2  to  3  cubic  feet  of  air  per  minute  was  a  safe  and  sufficient  supply 
for  each  person,  it  is  not  surprising  that  he  should  think  that  many 
people  demand  too  much.  He  says,  "  There  are,  in  England,  many 
persons  who,  under  all  circumstances,  call  out  for  open  fires  and  open 
windows,  and  by  the  cold  currents  and  other  concomitants  of  a  ventila- 
tion more  than  necessary,  prodigiously  waste  fuel  and  injure  or  kill 
their  children  and  friends  by  catarrh,  rheumatism,  etc."  In  later  years 
Dr.  Arnott  became  convinced  that  2  or  3  cubic  feet  of  air  per 
minute  are  not  enough — but  all  his  views  of  the  subject  are  from  the 
point  of  view  of  an  ingenious  mechanician  and  physicist — with  little 
reference  to  the  physiological  needs  of  the  living  human  body. 

A  very  valuable  work  on  heating  is  that  of  Mr.  Hood,  the  first 
edition  of  which  appeared  in  1837,  and  was  devoted  mainly  to  heating 
by  hot  water.  The  fifth  edition  appeared  in  1879.  Ventilation  is  only 
considered  incidentally. 

In  1835  Dr.  David  Boswell  Reid  was  employed  to  improve  the 
heating  and  ventilation  of  the  Houses  of  Parliament,  the  old  systems 
of  which  had  been  destroyed  by  fire.  As  the  result  of  experiments 
made  in  Edinburgh,  he  decided  that  the  quantity  of  air  to  be  warmed 
and  passed  through  the  chamber  must  be  much  greater  to  secure  satis- 
factory results  than  any  of  his  predecessors  had  supposed  to  be  neces- 
sary, and  that  the  area  of  clear  opening  for  discharge  of  air  should  be 
50  square  feet,  instead  of  19  square  feet,  as  had  been  provided  by  the 
Marquis  de  Chabannes.  He  provided  for  the  greatest  possible  diffu- 
sion of  the  incoming  air,  having  nearly  a  million  of  perforations  in  the 
floors,  seats,  etc.,  for  that  pfurpose,  and  made  elaborate  arrangements 
for  filtering,  warming  and  tempering  the  air  supply.  The  results  ap- 
pear to  have  been  very  satisfactory,  and  Dr.  Arnott's  statement  was 
no  doubt  correct,  that  "  Until  the  late  House  of  Commons  existed  as 
ventilated  by  Dr.  Reid,  there  was  never  in  the  world  a  room  in  which 
500  persons  or  more  could  sit  for  ten  hours  in  the  day,  and  day  after 
day,  for  long  periods,  not  only  with  perfect  security  to  health,  but 
with  singular  comfort." 

Dr.  Reid  published  the  results  of  his  experiments  and  observa- 
tions in  1844,  in  the  form  of  a  large  octavo  volume  entitled,  "Illus- 
tration of  the  Theory  and  Practice  of  Ventilation,  etc.,"  which  is  still 


36  HISTORY    AND    LITERATURE. 

one  of  the  most  suggestive  and  interesting  works  in  existence  on  this 
subject.  When  the  new  Houses  of  Parliament  were  constructed  Dr. 
Reid  was  employed  to  arrange  their  heating  and  ventilation,  but  be- 
came involved  in  controversies  with  the  architect,  and  the  result  was 
that  he  lost  his  position.  He  then  came  to  the  United  States,  and  in 
1858  published  at  New  York  a  work  entitled,  "  Ventilation  in  Ameri- 
can Dwellings,"  which,  however,  was  not  a  success.  He  was  suc- 
ceeded as  " ventilator"  to  the  Houses  of  Parliament  by  Mr.  Gurney, 
who  advocated  downward  ventilation,  ventilation  by  steam  jets,  and 
several  other  schemes,  some  of  which  were  tried  and  proved  failures; 
while  others  were  never  tried.  The  principal  change  which  he  made 
was  in  the  use  of  steam  heat  instead  of  hot  water.  He  was  suc- 
ceeded by  Dr.  Percy,  whose  reports  on  the  ventilation  of  the  Houses 
of  Parliament  are  among  the  best  of  this  kind  of  literature. 

In  1856,  the  General  Board  of  Health,  of  England,  appointed  a 
commission  to  inquire  into  the  best  practical  methods  of  warming  and 
ventilating  dwelling-houses.  The  report  of  this  commission,  which 
was  composed  of  William  Fairbairn,  James  Glaisher  and  Charles 
Wheatstone,  was  published  as  a  folio  blue  book,  in  1857.  Prof.  Lyon 
Playfair,  who  had  been  named  on  the  commission,  was  unable  to  serve. 
This  report  deals  mainly  with  the  results  of  experiments  on  various 
forms  of  grates  and  stoves  suitable  for  heating  dwelling-houses,  and 
the  most  interesting  part  of  it  as  regards  ventilation  is  given  in  the 
appendix  in  the  form  of  a  paper  on  the  Chemical  Relations  of  Ventila- 
tion, by  Henry  E.  Roscoe,  in  which  are  given  the  results  of  a  number 
of  experiments  made  by  himself,  and  also  of  a  number  made  by  Pro- 
fessor von  Pettenkofer,  in  Munich.  Professor  Roscoe  remarks  that  there 
is  great  need  of  precise  information  upon  two  points — viz.:  i.  When  is, 
and  when  is  not,  a  closed  inhabited  atmosphere  unhealthy?  2.  How 
much  ventilation  or  change  of  air  is  effected  in  a  particular  room  from 
what  may  be  termed  accidental  sources — that  is,  from  leakage,  per- 
meation of  walls,  opening  of  doors,  etc.?  To  the  first  question  he 
replies  that  no  definite  answer  can  be  given.  As  regards  the  second, 
he  concludes  that  the  amount  of  ventilation  from  accidental  sources  is 
larger  than  had  been  supposed,  but  that,  "under  all  circumstances,  an 
artificial  ingress  for  fresh  air  is  essential."  The  special  value  of  his 
work  consists  in  the  introduction  of  the  carbonic  acid  test,  as  employed 
by  von  Pettenkofer,  as  a  measure  of  the  amount  of  ventilation  actually 
going  on. 

The  writings  of  Frederick  Edwards,  Jr.,  upon  grates,  fireplaces, 
chimneys,  etc.,  which  appeared  between  1864  and  1870,  are  all  worth 


HISTORY    AND    LITERATURE.  37 

reading,  and  especially  so  is  his  treatise  on  the  ventilation  of  dwelling- 
houses,  published  in  1868. 

In  France  the  history  of  ventilation  has  been  mainly  connected 
with  its  application  to  hospitals,  and  when,  towards  the  end  of  the 
eighteenth  century,  Lavoisier  announced  his  discoveries  of  the  chemi- 
cal composition  of  the  air  and  the  physiological  importance  of  oxygen, 
it  was  to  hospitals  that  he  suggested  the  application  of  the  practical 
conclusions  to  be  drawn  from  these  discoveries  by  undertaking  to 
furnish  a.  constant  supply  of  fresh  air  to  the  inmates.  According  to 
Bertin-Sans  (Diet.  ency.  des  sc.  med.,  Series  V.,  Vol.  2,  Paris,  1886, 
article  %<  Ventilation"),  the  first  trace  of  a  project  for  the  ventilation  of 
a  public  building  in  France  is  found  in  1840,  when  Darcet  proposed  to 
ventilate  the  Necker  Hospital  in  Paris,  but  the  plan  was  not  carried 
out.  In  1843,  in  his  "  Traite  de  la  chaleur,"  Peclet  states  that  the  only 
hospital  in  France  that  had  ventilating  arrangements  was  that  of  Alais. 

In  1846  a  system  of  ventilation  combined  with  heating,  known  as 
le  sysftme  Duvoir,  was  applied  to  one  of  the  pavilions  of  the  Hospital 
Beaujon,  and  a  number  of  experiments  and  observations  made  on  this 
showed  that,  under  ordinary  circumstances,  60  cubic  meters  of  air  per 
bed  per  hour  was  scarcely  sufficient,  and  that  in  the  surgical  wards  it 
was  not  sufficient  to  keep  them  free  from  odor. 

In  the  construction  of  the  Hospital  Lariboisiere  in  1853  two  sys- 
tems were  tried,  one  of  aspiration,  the  other  of  insufflation,  the  results 
being,  according  to  Grassi's  report,  in  favor  of  the  latter,  but  neither 
of  them  were  entirely  satisfactory — for  neither  of  them  was  arranged  to 
provide  a  sufficient  quantity 'of  air. 

In  Germany,  as  in  France,  some  of  the  most  important  contribu- 
tions to  ventilation  have  been  made  in  connection  with  hospital  con- 
struction, and  especially  in  the  plans  of  large  hospitals  constructed  in 
recent  years  in  Berlin  and  Hamburg.  The  descriptions  and  plans  of 
the  Berlin  City  Hospital  at  Friedrichshain,  and  of  the  Military  Hos- 
pital at  Tempelhof,  both  prepared  by  the  architects,  Gropius  & 
Schmieden,  are  especially  interesting  in  this  respect. 

The  principal  systematic  German  work  on  the  subject  is  that 
of  Wolpert,  the  title  of  which  is  given  in  the  list  at  the  end  of  this 
chapter. 

The  investigations  into  the  sanitary  condition  of  the  English 
Army,  which  inquiries  were  brought  about  by  the  heavy  losses  of  the 
Crimean  War,  and  the  resulting  reports  of  the  Commission  on  the 
sanitary  state  of  the  army  made  in  1857,  and  of  the  Commission  there- 
upon appointed  for  improving  the  sanitary  condition  of  barracks  and 


38  HISTORY    AND    LITERATURE. 

hospitals  were  the  means  of  directing  special  attention  to  the  import- 
ance of  sufficient  air  supply  as  a  means  of  preserving  the  health  and 
efficiency  of  troops.  Between  1857  and  1860  the  experiments  of 
von  Pettenkofer,  Roscoe  and  other  physiologists  and  chemists  had 
shown  that  the  old  ideas  as  to  the  amount  of  air  required  to  so  dilute 
the  exhalations  of  men  that  there  should  be  no  unpleasant  odor — 
were  totally  inadequate — and  the  data  collected  by  the  Army  Sanitary 
Commission  showed  that  ill  health  and  excessive  mortality  prevailed 
among  the  troops  in  proportion  to  the  defects  in  the  air  supply  of 
their  barracks.  The  Barracks  Commissioners  fixed  20  cubic  feet  of 
fresh  air  per  minute,  or  1,200  cubic  feet  per  hour  per  man  as  the 
minimum  requirement.  In  1860  General  Morin  gave  the  figures 
required  for  barracks  as  1,059  cubic  feet  per  hour  by  day  and  twice 
that  amount  at  night  for  each  man,  and  in  the  first  edition  of  his 
"  Manual  of  Hygiene,"  published  in  1864,  Dr.  Parkes  states  that  at 
least  2,000  cubic  feet  per  hour  must  be  given  to  entirely  free  the  air 
from  unpleasant  odor. 

From  this  time  on  it  has  been  well  known  to  those  familiar  with 
the  subject  that  to  secure  satisfactory  ventilation  large  amounts  of  air 
must  be  introduced  and  distributed,  and  it  is  the  settlement  of  this 
point  that  has  done  away  with  much  of  the  useless  theories  and  specula- 
tions of  former  years.  It  is  mainly  to  the  teachings  of  von  Pettenkofer 
and  his  school  that  what  may  be  called  the  chemical  test  for  ventila- 
tion has  come  into  use  during  the  last  25  years,  and  is  now  the  one 
that  is  chiefly  relied  upon,  as  will  be  explained  in  a  future  chapter. 

One  of  the  most  valuable  manuals  on  ventilation  is  "  A  Practical 
Treatise  on  Ventilation  and  Warming,"  by  Dr.  Morrill  Wyman,  pub- 
lished in  Boston,  in  1846.  In  a  comparatively  brief  space  it  sums  up 
what  is  really  useful  of  the  work  of  Peclet ;  states  the  general  principles 
of  ventilation  in  a  clear,  concise  style,  and  in  a  form  which,  as  a  means 
of  instruction  for  the  ordinary  reader,  can  hardly  be  surpassed  ;  gives 
good  illustrations  of  the  methods  used  in  various  kinds  of  buildings, 
and  of  the  results  obtained,  and  is  one  of  the  few  books  on  heating  and 
ventilation  which  advocates  no  patent  or  proprietary  apparatus. 

Of  later  American  writers  on  this  subject,  I  will  refer  to  but 
two — Mr.  Robert  Briggs,  a  well-known  American  engineer,  who  died 
in  1882,  and  Mr.  Baldwin,  who  is  still  living.  Mr.  Briggs  was  a  prac- 
tical mechanical  engineer,  who  was  for  a  number  of  years  in  charge  of 
the  works  of  a  large  manufacturing  establishment  in  Philadelphia,  and 
had  much  to  do  with  the  making  of  steam-heating  apparatus  and  of 
fans  for  mechanical  ventilation.  He  wrote  no  systematic  treatise  on 


HISTORY    AND    LITERATURE.  39 

the  subject,  but  presented  some  valuable  papers  before  engineering 
societies,  and  contributed  much  interesting  matter  to  the  earlier  volumes 
of  The  Engineering  Record,  and  in  this  way,  as  well  as  through  those 
trained  in  the  shops  under  his  direction,  he  has  exercised  a  very  con- 
siderable influence  on  the  details  of  apparatus  and  methods  employed 
in  the  Middle  and  Western  States  for  heating  and  ventilating  during 
recent  years. 

Mr.  Baldwin  has  also  written  much  on  heating  for  The  Engineering 
Record,  and  his  books  on  steam  and  on  hot-water  heating  are 
standard  authorities  for  American  practice,  and  incidentally  in- 
clude some  interesting  matter  relating  to  the  ventilation  of  particular 
buildings. 

On  the  subject  of  heating  and  ventilating  legislative  assembly 
halls  several  reports  of  interest  have  appeared  in  the  United  States. 
Among  these  may  be  mentioned  the  report  of  the  Committee  on  Pub- 
lic Buildings  of  the  House  of  Representatives  of  the  State  of 
Massachusetts  upon  the  ventilation  of  Representatives'  Hall,  made 
April  2,  1849  ;  the  report  of  the  Special  Committee  of  the  same 
House  upon  the  same  subject  made  in  January,  1865  ;  the  report 
upon  the  ventilation  of  both  Houses  of  Congress,  presented  to  the 
House  of  Representatives  in  1866  ;  the  report  on  the  ventilation  of 
the  Hall  of  the  House,  presented  to  the  House  of  Representatives  in 
February,  1878,  and  the  report  presented  to  the  same  body  in  June, 
1884. 

Of  the  above,  the  Massachusetts  Report  of  1865,  is  mainly  an 
argument  in  favor  of  downward  ventilation.  The  report  made  to  Con- 
gress in  1865  is  especially  valuable  because  it  contains  the  results  of 
an  extended  series  of  observations  and  air  analyses  made  by  Dr.  Charles 
M.  Wetherell  in  the  Halls  of  Congress  under  different  circumstances. 
With  the  official  reports  on  the  ventilation  of  the  Capitol  at  Washing- 
ton should  be  mentioned  the  report  of  Mr.  Robert  Briggs  on  this 
subject,  made  in  1876,  in  which  the  original  plans  for  heating 
and  ventilation  are  described.  The  conclusions  of  these  reports 
will  be  given  in  the  description  of  the  ventilation  of  the  House 
of  Representatives  which  will  be  found  in  a  subsequent  chapter  of 
this  book. 

The  following  is  a  list  of  some  of  the  more  important  and  inter- 
esting books  relating  to  ventilation  which  have  been  published  up  to 
the  present  time.  Other  works  and  papers  relating  to  the  ventilation 
of  mines  and  of  special  classes  of  buildings  will  be  referred  to  in  the 
chapters  devoted  to  those  subjects. 


40  LITERATURE    OF    VENTILATION. 

GAUGER  (N.) — Lamecanique  du  feu,  ou  1'art  d'en  augmenter  les  effets,  and  d'en 
dimirmer  la  depense,  Contenant  le  traitc  de  nouvelles  cheminees  [etc.],  par 
N.  G  *  *  *  .  X  ,  267  pp.,  4!.,  12  pi.,  Svo.  Amsterdam:  1714. 

Fires  Improved;  or,  A  New  Method  of  Building  Chimneys,  so  as  to 

Prevent  their  Smoking.     158  pp.,  Svo.     London:  1736. 

HALES  (STEPHEN) — A  Description  of  Ventilation ;  whereby  great   quantities   of 
fresh  air  may  with  ease  be  conveyed  into  mines,  gaols,  hospitals,  work- 
houses and  ships,  in  exchange  for  their  noxious  air.     An  account  also  of 
their  great  usefulness  in  many  other  respects;  as  in  preserving  all  sorts  of 
*  grain  dry,  sweet,  and  free  from  being  destroyed  by  weevels,  both  in  gran- 
aries and  ships,  and  in  preserving  many  other  sorts  of  goods;  as  also  in 
drying  corn,  malt,  hops,  gunpowder,  etc.,  and  for  many  other  useful  pur- 
poses, which  was  read  before  the  Royal  Society  in  May,  1741.     Svo.     Lon- 
don: 1743. 
-  A  Treatise  on  Ventilators.  In  two  parts,  in,  346  pp.,  Svo.  London:  1758. 

GENNETE. — Purification  de  1'air  croupissant  dans  les  hopitaux,  les  prisons,  et 
les  vaisseaux  de  mer.  113  pp.,  i  pi.,  Svo.  Nancy:  1767. 

Report  of  the  Committee  of  the  House  of  Commons  on  Ventilation,  Warming, 
and  Transmission  of  Sound;  abbreviated,  with  notes,  by  W.  S.  Inman. 
London:  John  Weale.  1836. 

URE  (A.) — An  Experimental  Inquiry  into  the  Modes  of  Warming  and  Venti- 
lating Apartments,  in  Reference  to  the  Health  of  the  Inmates.  8vo.,  n.  p. 
1836. 

TREDGOLD  (THOMAS) — The  Principles  of  Warming  and  Ventilating  Public 
Buildings,  Dwelling-Houses,  Manufactories,  Hospitals,  etc.  Third  edi- 
tion, to  which  is  now  added  an  appendix  by  T.  Bramah,  on  Heating  by 
Means  of  Warm  Water,  etc.  324  pp.,  12  pi.,  Svo.  London:  1836. 

ARNOTT  (N.) — On  Warming  and  Ventilating,  with  Directions  for  Making  and 
Using  the  Thermometer  Stove.  Svo.  London:  1838. 

REID  (DAVID  BOSWELL) — Illustrations  of  the  Theory  and  Practice  of  Ventila- 
tion, with  Remarks  on  Warming,  Exclusive  Lighting,  and  the  Communi- 
cation of  Sound.  XX.,  451  pp.,  Svo.  London:  1844. 

BERNAN  (W.) — [MEIKLEHAM  (R.)]. — On  the  History  and  Art  of  Warming  and 
Ventilating  Rooms  and  Buildings  by  Open  Fires,  Hypocausts,  German, 
Dutch,  Russian  and  Swedish  Stoves,  Steam,  Hot  Water,  Heated  Air, 
Heat  of  Animals,  and  Other  Methods.  2  vols.  in  i,  i2mo.  London:  1845. 

WYMAN  (MORRILL)— A  Practical  Treatise  on  Ventilation.  XVI.,  419  PP- 
Boston:  1846. 

Report  (Second)  From  the  Select  Committee  on  Ventilation  and  Lighting  of 
the  House  (with  Minutes  of  Evidence  and  Appendix).  670  pp.,  roy.  Svo. 
London:  1852. 

PECLET  (E.) — Nouveaux  documents  relatifs  au  chauffage  et  a  la  ventilation  des 
etablissements  publics,  suivis  de  nouvelles  recherches  sur  le  refroidisse- 
ment  et  la  transmission  de  la  chaleur  [pour  servir  de  supplement  a  la 
seconde  edition  du  Traite  de  la  chaleur.]  4to.  Paris:  1854. 


LITERATURE    OF    VENTILATION.  4! 

ARNOTT  (N.) — On  the  Smokeless  Fireplace,  Chimney  Valves,  and  Other 
Means,  Old  and  New,  of  Obtaining  Healthful  Warmth  and  Ventilation . 
8vo.  London:  1855. 

PETTENKOFER  (M.) — Ueber  den  Luf  twechsel  in  Wohngebauden .  8vo.  Mun- 
chen:  1858. 

REID  (D.  B.) — Ventilation  in  American  Dwellings;  to  which  is  added  an  in- 
troductory outline  of  the  progress  of  improvement  in  ventilation  by 
Elisha  Harris.  8vo.  New  York:  1858. 

PECLET  (E.) — Traite  de  la  chaleur  consideree  dans  ses  applications.  3  ed. 
8vo.  Paris:  1 860-61. 

RITCHIE  (ROBERT). — A  Treatise  on  Ventilation,  Natural  and  Artificial.  XVI. 
232pp.,8vo.  London:  1862. 

MORIN  (ARTHUR). — Mecanique  Pratique.  Etudes  sur  la  ventilation.  610, 
407  pp.,  16  pi.,  8vo.  Paris:  1863. 

House  of  Representatives,  39th  Congress,  ist  Session,  Ex.  Doc.  No.  100. 
Warming  and  Ventilating  the  Capitol.  96  pp.,  8vo.  Dated  May  7,  1866. 

MORIN  (A.) — Manuel  pratique  duchauff age  etde  la  ventilation.  8vo.  Paris,  1868. 

EDWARDS  (F.) — On  the  Ventilation  of  Dwelling  Houses  and  the  Utilization  of 
Waste  Heat  From  Open  Fireplaces.  VIII.,  168  pp.,  8vo.  London:  1868. 

GREAT  BRITAIN,  COMMISSIONERS  OF  PATENTS.  Patents  for  Inventions,  Abridg- 
ments of  Specifications  Relating  to  Ventilation.  A.  D.  1632-1866.,  i2mo. 
London:  1872. 

DEGEN  (L.) — Practisches  Handbuch  fttr  Einrichtungen  der  Ventilation  und 
Heizung  in  Offentlichen  und  Privatgebauden  nach  dem  System  der 
Aspiration.  Unter  Zugrundelegung  von  Morin's  Manuel  du  Chauffage  et 
de  la  Ventilation.  2d.,  8vo.  Mtionchen:  1878. 

House  of  Representatives,  45th  Congress,  2d  Session.  Report  No.  119.  Ven- 
tilation of  the  Hall  of  the  House.  16  pp.,  8vo.  Dated  February  4,  1878. 

HOOD  (C.) — A  Practical  Treatise  on  Warming  Buildings  by  Hot  Water,  Steam 
and  Hot  Air,  etc.  5th  ed.  London:  1879.  (First  edition  was  in  1837.) 

VALERIUS  (H.) — Les  applications  de  la  chaleur,  avec  un  expose  des  meilleurs 
systemes  de  chauffage  et  de  ventilation.  8vo.  Paris:  1879. 

PLANAT  (P.) — Cours  de  construction  civile,  Premiere  partie  ;  Chauffage  et  ven- 
tilation des  lieux  habites.  4to.  Paris  :  1880. 

WOLPERT  (A.) — Theorie  und  Praxis  der  Ventilation  und  Heizung.  2,  Aufl., 
8vo.  Braunschweig:  1880. 

PUTNAM  (J.  P.)— The  Open  Fireplace  of  all  Ages.     8vo.     Boston  :  1881. 

BILLINGS  (J.  S.) — The  Principles  of  Ventilation  and  Heating,  and  Their  Prac- 
tical Application.  8vo.  New  York  :  1884. 

Reports  (first  and  second)  from  the  Select  Committee  on  the  Ventilation  of  the 
House.  Folio.  London  :  1886. 

Traite  de  physique  industrielle,  production  et  utilisation  de  la  chaleur,  par  L 
Ser.  Torne  n.  2d  part  avec  la  collaboration  de  M.  M.  L.  Carelle  et 
E.  Herscher.  8vo.  Paris :  1892. 


T 


CHAPTER  III. 

THE      ATMOSPHERE. 
COMPOSITION    AND    PHYSICAL    PROPERTIES. 

*HE  atmosphere  is  the  gaseous  envelope  which  surrounds  the  earth, 
forming  an  aerial  ocean  in  which  we  move  about.  This  atmos- 
phere is  a  mixture  of  gases  and  vapors,  two  of  which,  oxygen  and 
nitrogen,  make  up  the  great  bulk  and  are  found  everywhere  in  almost 
constant  proportions.  Besides  these  there  are  always  present  carbonic 
acid,  watery  vapor,  and  ammonia,  or  some  of  its  compounds.  As  the 
result  of  a  vast  number  of  analyse^  made  in  different  parts  of  the  world, 
the  proportions  of  the  different  ingredients  in  normal  air  are  found  to 
be  in  100  parts  by  volume,  an  average  of  nitrogen,  78.30;  oxygen, 
20.70;  carbonic  acid,  0.03;  water,  0.8  to  i.o;  ammonia,  a  trace.  The 
principal  variations  from  this  mean  in  different  localities  consist  in  in- 
crease in  the  proportions  of  carbonic  acid,  water  and  ammonia,  and  in  the 
addition  of  various  other  gases,  which  last,  however,  may  be  considered 
as  merely  local  impurities.  The  normal  atmosphere  is  not  a  chemical 
combination  of  the  different  factors  composing  it,  but  a  mere  mechani- 
cal mixture.  If  it  were  a  chemical  compound  of  definite  composition, 
the  problems  of  ventilation  would  be  of  a  very  different  nature  from 
those  presented  under  existing  circumstances.  The  mixing  of  these 
constituents  due  to  changes  in  temperature,  mechanical  action  of 
winds,  and  to  natural  diffusion  between  gases  of  different  natures  is  so 
%  perfect  that  analyses  of  the  external  air  in  the  most  widely  separated 
localities  give  results  which  vary  but  little  from  the  above  figures,  The 
proportion  of  oxygen  and  nitrogen  in  the  air  taken  near,  the  surface  of 
the  sea  many  miles  from  land,  or  upon  mountain  tops,  differs  as  to  the 
proportion  of  the  oxygen  and  nitrogen  which  it  contains  in  hardly  an 
appreciable  degree  from  that  taken  in  the  streets  of  a  city  or  over  the 
prairies  of  the  West.  The  perfection  of  this  mixing  of  the  gases  in  the 
atmosphere  is  shown  by  the  results  obtained  by  air  analyses  made  in 
large  cities.  If  we  take  the  city  of  London,  for  example,  it  is  esti- 
mated that  90,000  tons  of  carbonic  acid  are  thrown  into  its  atmosphere 


COMPOSITION    OF    THE    ATMOSPHERE.  43 

daily,  and  yet  analyses  of  the  air  at  this  place  show  an  increase  of  not 
mor  than  one-  part  in  10,000  of  this  gas  over  the  proportion  found  in 
the  suburbs  or  rural  districts.  The  uniformity  of  the  mixture,  however, 
only  obtains  in  places  where  the  air  is  free  to  move  in  every  direction 
under  the  action  of  differences  of  temperature  or  of  winds  coming  from 
without.  In  places  more  or  less  inclosed,  where  the  winds  have  no 
action,  such,  for  example,  as  sewers,  or  inclosed  courts,  and  where  de- 
composition of  organic  matters  is  going  on,  various  substances  may  be 
added  to  the  air  in  such  proportions  as  to  become  susceptible  of 
analysis  and  necessary  to  be  considered  in  respect  to  the  comfort  and 
health  of  those  living  in  the  vicinity.  Among  these  may  be  grouped 
carbon  monoxide,  ammoniacal  compounds,  sulphuretted  hydrogen 
and  sulphuric  and  sulphurous,  nitric  and  nitrous  acids.  In  deep 
wells  the  proportion  of  carbonic  acid  which  gains  entrance  from 
the  surrounding  soil  may  reach  very  high  proportions,  since  the  only 
method  of  removing  the  excess  is  through  the  process  of  diffusion, 
which  is  overbalanced  by  the  rate  of  production  of  this  gas.  Thus 
accumulation  of  this  gas  results,  which  may  render  the  air  of  the 
well  incapable  of  supporting  respiration  or  of  maintaining  the  flame  of 
a  candle,  although  the  upper  part  is  freely  open  to  the  external,  com- 
paratively pure  air. 

Among  the  constituents  of  the  atmosphere,  although  subject  to 
great  variations,  it  has  been  usual  to  reckon  a  gas  known  by  the  name 
of  ozone,  which  by  most  chemists  is  considered  to  be  an  allotropic 
form  of  oxygen.  As  prepared  in  the  laboratory  this  is  characterized 
by  a  peculiar  odor  and  by  having  special  oxidizing  powers,  and  its 
presence  in  the  atmosphere  has  been  considered  so  important  a  matter 
that  special  methods  have  been  devised  for  its  quantitative  estimation, 
and  at  certain  meteorological  stations  a  daily  record  of  its  variations 
has  been  kept.  It  has,  however,  long  been  known  that  the  methods 
of  testing  for  it  are  liable  to  produce  great  errors,  and  a  recent  work 
upon  the  subject  seems  to  indicate  that  much,  if  not  all,  of  what  have 
been  supposed  to  be  the  characteristic  reactions  of  ozone  in  the  air  are 
really  due  to  nitrous  acid,1  and  that  it  is  very  doubtful  as  to  whether 
the  supposed  allotropic  oxygen  exists  in  the  free  atmosphere. 

Of  the  fundamental  factors,  nitrogen  and  oxygen,  going  to  make 
up  our  air,  the  nitrogen  possesses  apparently  no  hygienic  significance 
whatever.  Its  only  office  seems  to  be  the  dilution  of  the  otherwise  too 
energetic  oxygen.  It  plays  no  direct  biological  role  in  either  the 

,  Bull.  soc.  Chimique  de  Paris,  September  and  November,  1889. 


44  COMPOSITION    OF    THE    ATMOSPHERE. 

animal  or  vegetable  kingdom,  and  is  therefore  from  a  hygienic  stand- 
point of  but  little  interest. 

The  oxygen,  on  the  other  hand,  is  of  most  vital  importance  to  all 
living  things — without  it  life  would  cease.  Fortunately  the  stock  cf 
oxygen  existing  in  the  air  is  so  great  and  the  provisions  for  its  con- 
stant circulation  so  perfect  that  there  is  but  little  fear  of  its  exhaustion. 

Throughout  the  animal  kingdom  oxygen  is  essential  to  the  tissue 
changes  which  go  to  make  up  what  we  understand  as  life.  As  a  result 
of  its  action  upon  the  tissues  of  the  animal  bodies  certain  products  are 
given  off,  most  conspicuous  among  them  being  the  carbonic  acid 
thrown  off  from  the  lungs  in  the  process  of  respiration.  Some  idea 
of  the  amount  of  carbonic  acid  given  off  daily  by  the  animal  world 
may  be  formed  when  one  considers  that  from  each  adult  human  being 
it  is  estimated  464.4  litres  (16.25  cubic  feet),  are  excreted  in  24  hours. 

No  doubt  the  influence  of  this  daily  pollution  would  after  a  time 
be  felt  by  the  inhabitants  of  the  earth,  were  it  not  for  the  peculiar 
functions  of  certain  of  the  vegetable  kingdom. 

Many  members  of  the  plant  world — those  containing  the  green 
coloring  matter  known  as  chlorophyl — under  the  influence  of  sunlight 
have  the  power  of  taking  up  this  carbonic  acid,  working  it  over  in 
their  tissues,  and  giving  out  free  oxygen  as  an  excretory  product.  In 
this  way  a  constant  proportion  in  the  amount  of  this  all-important  gas 
in  the  air  is  maintained.  So  great  is  the  stock  of  oxygen  in  the  air, 
and  so  active  its  reproduction  by  thechlorophyl-containing  plants,  that 
its  exhaustion  by  animal  life  is  quite  out  of  the  question. 

It  has  been  estimated  that  if  all  vegetables  should  cease  to  repro- 
duce this  gas,  and  animal  life  continue  as  it  now  is,  that  about  eighteen 
thousand  years  would  be  necessary  for  a  reduction  of  i  per  cent,  in  the 
amount  of  oxygen  now  present  in  the  air. 

It  is,  however,  quite  possible  that  a  change  in  the  proportion  of 
oxygen  may  ultimately  be  produced  by  the  burning  of  fuel.  In 
the  Lancet  of  August  12,  1882,  Dr.  T.  H.  Walker  takes  the  ground 
that  the  carbon  formerly  extracted  out  from  the  atmosphere  and 
stored  up  in  coal  is  now  being  rapidly  returned  to  it  chiefly  through 
the  influence  of  the  combustion  of  coal.  Animal  respiration  and  the 
decay  of  plants  have  very  little  permanent  influence  on  the  amount  of 
carbonic  acid  in  the  atmosphere,  for  it  is  simply  a  process  of  circula- 
tion, and  the  animal  only  gives  back  to  the  atmosphere  what  has  pre- 
viously been  absorbed  by  the  plants  on  which  the  animal  feeds.  In 
the  burning  of  limestone,  there  is  simply  a  return  to  the  air  what  the 
animals  from  the  shells  of  which  the  limestone  is  built  up  have  pre- 


COMPOSITION    OF    THE    ATMOSPHERE.  45 

viously  absorbed.  A  certain  amount  is  given  out  by  volcanoes  and 
caverns  in  the  depths  of  the  earth,  but  this  is  of  small  importance. 
The  amount  of  coal  annually  consumed  throughout  the  world  is  esti- 
mated by  Bessemer  at  400,000,000  tons,  giving  336,000,000  tons  of 
carbon,  thus  giving  out  1,232  million  tons  of  carbonic  acid  annually  to 
the  atmosphere.  The  total  weight  of  the  atmosphere  is  estimated  at 
5,210  billion  tons,  including  about  three  billion  tons  of  carbonic  acid. 
He  concludes  that  the  air  will  become  injurious  to  life  from  the 
influence  of  carbonic  acid  when  one-sixth  part  of  the  coal  known  at 
present  is  consumed. 

The  possibility  of  such  an  increase  of  the  proportion  of  carbonic 
acid  in  the  atmosphere  as  to  have  a  definite  influence  upon  the  vege- 
table and  animal  life  of  the  globe,  said  increase  being  due  to  the  com- 
bustion of  the  available  coal,  has  also  been  discussed  by  General  Isaac 
J.  Wistar,  in  a  paper  contained  in  the  Proceedings  of  the  Academy  of 
Natural  Sciences  of  Philadelphia,  for  January  26,  [892.  He  concludes 
from  the  data  given  that  the  amount  of  mineable  coal  may  be  taken  as 
equal  to  nearly  i  inch  in  thickness  over  the  land  surface  of  the  earth, 
and  that  if  this  thickness  be  taken  as  .8371  inch  its  complete  combus- 
tion would  remove  i  per  cent,  of  the  tree  oxygen  of  the  atmosphere 
and  add  to  the  air  a  little  over  three-tenths  of  i  per  cent,  by  weight  of 
carbonic  acid. 

Supposing  these  premises  to  be  correct,  it  is  possible  that  some 
compensatory  changes  in  animal  organization  would  follow,  but  the 
direct  result  of  this  change  in  the  composition  of  the  air  would,  of 
course,  be  very  gradual.  As  will  be  seen  in  the  section  relating  to 
carbonic  acid  determinations,  there  is  no  evidence  of  any  increase  in 
its  proportion  in  the  atmosphere  within  the  last  30  years,  during  which 
the  combustion  of  fuel  has  been  at  its  height,  and  until  such  increase 
to  the  amount  of  i  part  in  10,000  has  been  demonstrated,  it  will  not 
be  worth  while  to  sound  an  alarm  and  attempt  to  check  the  consump- 
tion of  fuel  for  this  reason  only. 

The  amount  of  carbonic  acid  in  the  atmosphere  arising  from  the 
manifold  processes  incidental  to  life  in  both  animal  and  vegetable 
kingdoms,  and  to  the  many  chemical  changes  both  natural  and  arti- 
ficial constantly  going  on  over  the  surface  of  the  earth  is  found  to 
experience  only  a  very  slight  variation.  In  general,  an  average  of 
from  3  to  4  parts  in  10,000  parts  of  air  may  be  taken  as  normal.  As  i 
stated  above,  under  certain  abnormal  conditions,  this  amount  may  be 
subjected  to  slight  increase,  but  such  an  increase  is  only  local  and 
temporary,  and  the  rise  in  amount  is  quickly  caused  to  disappear 


46  VAPORS    IN    THE    ATMOSPHERE. 

through  mechanical  action  of  winds  and  the  natural  diffusion  con- 
stantly in  progress  between  gases  of  different  nature. 

In  these  amounts  the  gas  is  of  itself  of  no  biological  significance 
whatever.  But  as  we  shall  see  when  we  come  to  consider  the  air  of 
inclosed  spaces  occupied  by  human  beings,  a  rise  or  fall  in  the 
quantity  of  this  gas  present  will  indicate  other  parallel  changes  in  the 
air  which  may  be  of  the  greatest  moment. 

A  further,  and  perhaps  the  most  variable  normal  constituent  of 
the  atmosphere  is  water  in  the  form  of  vapor,  the  amount  of  which 
increases  and  decreases  with  every  rise  and  fall  of  temperature,  and 
likewise  with  the  opportunities  present  for  the  air  to  obtain  moisture. 
On  an  average,  the  air  may  be  said  to  contain  between  0.8  and  i.o 
part  per  cent  per  volume  of  water  in  the  form  of  vapor.  Only  rarely 
do  we  find  as  much  vapor  in  the  atmosphere  as  is  possible  for  it  to 
hold.  When  such  a  condition  exists  the  air  is  said  to  be  "saturated," 
that  is,  for  the  existing  temperature  there  is  so  much  invisible  vapor 
present  that  the  slightest  decrease  in  the  temperature  results  in  a 
condensation  of  a  portion  of  the  vapor  in  the  form  of  visible  water. 
This  point,  at  which  the  air  can  not  take  up  more  vapor  at  the  existing 
temperature,  or  loses  a  portion  of  its  vapor  by  condensation  if  its 
temperature  be  but  slightly  reduced,  is  known  as  its  "  Dew  Point." 

The  relative  amount  of  water  present  in  air  which  is  not  saturated 
is  usually  expressed  in  per  cent,  of  what  the  air  should  contain  at  the 
existing  temperature  were  its  condition  that  of  saturation.  This 
amount  is  expressed  by  the  term  "  Relative  Humidity."  The  actual 
amount  of  water  present  in  air  at  any  moment,  regardless  of  saturation, 
is  known  as  its  "Absolute  Humidity." 

The  variations  in  the  amount  of  aqueous  vapor  which  are  seen  to 
occur  in  the  air  at  different  points  on  the  earth's  surface  are  very 
great,  the  least  being  present  at  inland  places  of  constantly  low  tem- 
perature, the  greatest  amount  being  found  to  co-exist  with  large  water 
surfaces  and  constantly  high  temperature.  In  the  first  case  it  is  plain 
that  hut  small  amounts  of  vapor  should  be  expected  in  the  air; 
whereas,  under  the  latter  conditions  both  the  extent  of  water  exposed 
and  the  elevated  temperature  favor  evaporation,  and  hence  an  increase 
in  the  degree  of  humidity  in  the  surrounding  atmosphere.  For  the 
same  place,  daily  fluctuations  in  the  humid  condition  of  the  air  are  seen 
to  occur.  These  diurnal  variations  are  found  to  follow  certain  regular 
and  definite  laws  dependent  in  most  cases  upon  temperature  changes. 

For  points  on  the  sea  coast,  or  near  large  bodies  of  water,  the 
absolute  humidity  of  the  air  is  found  to  experience  a  gradual  increase 


COMPOSITION    OF    THE    ATMOSPHERE.  47 

from  sun-rise   until  about    2    o'clock   p.    M.,    when    a   corresponding 
diminution  sets  in  and  continues  until  sun-rise  again. 

For  inland  places  the  same  general  law  may  be  laid  down  for 
ths  winter  months,  but  in  summer  the  curve,  if  the  variations  are 
represented  graphically,  will  experience  a  slight  fall  and  rise  between 
the  hours  of  4  and  6  o'clock  p.  M.  After  6  p.  M.  the  decrease  in  the 
amount  of  vapor  is  gradual  until  sun-rise  the  following  morning,  when 
nearly  the  same  condition  should  be  found  as  existed  at  the  same  hour 
on  the  previous  morning. 

In  addition  to  the  normal  and  accidental  constituents  of  the  air 
which  have  already  been  mentioned,  there  are  constantly  present  solid 
particles.  These  solid  matters,  which  vary  in  amount  with  changing 
atmospheric  conditions,  are  for  the  most  part  simple  microscopic  par- 
ticles of  inorganic  matter,  in  the  form  of  dust,  the  result  of  wear  and 
tear  upon  the  earth's  surface,  or  they  may  be  of  organic  origin  and 
possess  distinct  biological  characteristics.  When  in  this  form  they  are, 
for  the  most  part,  vegetable  in  nature,  and  represent  the  family  of 
bacteria.  The  great  majority  of  bacteria  found  in  the  air  are  not 
floating  free  as  single  separate  individuals,  but  are  deposited  upon 
larger  dust  particles.  In  very  exceptional  cases,  these  organisms  may 
possess  the  power  of  producing  disease,  but,  as  a  rule,  it  may  be  safely 
said  that  the  bacteria  found  in  the  open  air  are  of  an  innocent  nature,  and 
indeed,  play  the  part  of  benefactors  to  humanity.  It  is  through  the 
agency  of  these  innocent  saprophytes  that  complex  dead  matters  are 
reduced  to  their  simpler  elementary  forms  and  returned  to  the  earth  to 
serve  as  nutrition  for  more  highly  organized  plants. 

It  is,  of  course,  not  impossible  for  disease-producing  organisms  to 
find  their  way  into  the  free  atmosphere,  but  here  they  meet  with  so 
many  conditions  unfavorable  to  their  existence,  and  are  distributed 
through  such  an  enormous  volume  of  air  that  their  detection  is  extremely 
improbable.  In  the  air  of  rooms  or  hospital  wards  containing  patients 
suffering  from  infectious  diseases,  the  conditions  are  quite  different,  as 
will  be  seen  when  we  come  to  treat  of  this  part  of  our  subject. 

From  what  has  been  said,  it  is  seen  that  our  air  is  fundamentally  a 
mixture  of  two  gases,  nitrogen  and  oxygen  ;  that  there  is  constantly 
present  a  pollution  of  from  3  to  4  parts  of  carbonic  acid  gas  to  10,000 
parts  of  air  ;  that  water  vapor  in  varying  amounts  is  present  in  most 
places ;  that  solid  particles,  in  amount  depending  upon  varying 
atmospheric  conditions,  and  of  both  organic  and  inorganic  nature,  are 
to  be  found,  and,  in  addition,  a  variety  of  accidental  gaseous  contami- 
nations may  now  and  then  be  detected. 


48  PHYSICS    OF    THE    ATMOSPHERE. 

What  has  been  said  thus  far  refers  entirely  to  the  air  as  we  find  it 
in  "the  open,"  that  is,  to  the  free  atmosphere.  An  acquaintance  with 
it  in  this  condition  is  essential  before  attempting  to  study  alterations 
in  its  constitution  resulting  from  processes  of  life. 

In  connection  with  the  mechanics  of  ventilation,  which  deal 
largely  with  movements  of  air,  and  the  means  of  producing,  directing 
and  regulating  them,  the  physical  properties  of  the  air  are  more 
important  than  its  chemical  composition,  and  it  is  necessary  to  study 
these  in  their  relations  to  different  conditions  of  temperature,  pressure 
and  presence  of  vapor  of  water.  Air  has  weight,  and  the  weight  of  a 
given  volume  of  air  differs  under  different  circumstances.  A  given 
volume,  for  instance  a  cubic  foot,  weighs  more  when  it  is  dry  than 
when  it  contains  moisture  if  the  temperature  and  pressure  be  the 
same  ;  it  weighs  more  at  a  lower  temperature  than  at  a  higher  one  if  - 
the  pressure  and  moisture  be  the  same,  and  its  weight  increases  with  * 
the  pressure  if  the  temperature  and  moisture  be  the  same.  Hence,  to 
determine  the  weight  of  a  given  volume  of  air  by  comparing  it  with  a 
standard  fixed  by  experiment,  it  is  necessary  to  know  not  only  the 
volume  but  the  temperature,  pressure  and  proportion  of  contained 
watery  vapor  of  the  air  to  be  measured.  And  since  most  of  the 
movements  of  masses  in  the  air  in  the  form  of  currents,  with  which 
ventilation  is  concerned,  are  due  to  differences  in  weight  between 
adjacent  equal  volumes  of  air,  it  is  desirable  that  the  causes  of  these 
differences  should  be  understood,  and  the  means  of  measuring  their 
effects  be  at  the  command  of  those  who  are  to  deal  with  problems  of 
this  kind. 

First,  then,  as  to  effects  of  temperature.  When  air  which  is  free 
to  expand,  or  which,  in  other  words,  is  under  constant  pressure,  is 
heated,  it  increases  in  volume  according  to  a  definite  law  which  is, 
that  for  each  degree  of  temperature  added  to  its  heat  it  expands  a  cer- 
tain constant  fraction  of  its  own  volume,  the  figure  representing  which 
is  known  as  the  co-efficient  of  expansion.  This  co-efficient  is  for  air 
0.003667  for  each  degree  centigrade  from  o.°  C.,  to  100°  C.,  or  on  the 
Fahrenheit  scale,  it  is  0.00236  for  each  degree  between  32°  and  212°  F. 
For  example,  i  cubic  centimeter  of  air  at  o.°  C.  will  make  1.003667  c.c. 
at  i°  C.,  or  1.03667  c.c.  at  10°  C.,  or  at  any  given  temperature  /",  it 
will  make  i  +  (0.003667  t°)  c.c.  In  like  manner,  i  cubic  foot  of  air  at 
32°  F.  will  become  1.00236  cubic  foot  at  33°  F.,  and  at  any  given  tem- 
perature /,  above  32°  on  the  Fahrenheit  scale  its  volume  will  be  found 
by  the  formula,  V=i-\-  (0.00236  x  (t  —  32)).  This  law  holds  good  so 
long  as  the  pressure 'is  constant,  no  matter  what  the  pressure  may  be. 


PHYSICS    OF    THE    ATMOSPHERE.  49 

The  alterations  experienced  by  a  volume  of  gas  under  varying 
conditions  of  pressure  stand  not  in  a  direct  relation,  as  in  the  case  of 
temperature,  but  are  inversely  proportionate  to  the  pressure.  (Boyle's 
Law.)  If  a  cubic  foot  of  gas  at  one  atmosphere  be  subjected  to  an 
additional  pressure  of  an  atmosphere,  its  volume  will  be  reduced  to 
one-half  of  a  cubic  foot;  if  to  four  atmospheres,  the  resulting  volume 
will  be  one-quarter  of  a  cubic  foot  —  or,  as  it  is  generally  expressed,  if 
under  a  pressure  of  b  millimetres  or  inches  of  mercury  the  volume  of  air 
is  expressed  by  r,  its  reduced  volume  VH  under  normal  conditions  of 
760  m.m.,  or  29.922  inches  of  mercury  may  be  found  by  the  following 
formula: 

v  :  vn  =  760  :  b  (not  as  b  to  760),  /. 

v  .  b 

vn  =  •  - 
760 

or  expressed  in  words,  to  reduce  any  volume  of  air  at  the  observed 
barometric  pressure  to  what  it  would  be  under  the  standard  pressure 
of  one  atmosphere,  multiply  the  observed  volume  by  the  observed 
pressure,  and  divide  the  result  by  the  normal  pressure  (760  m.m.,  or 
29.922  inches  of  mercury). 

But,  as  has  been  said,  the  volume  of  air  is  affected  also  by  tem- 
perature, and,  as  temperature  and  pressure  always  exist  together  in 
reducing  any  volume  of  air  to  standard  conditions,  both  factors  must 
be  taken  into  account. 

By  the  term,  standard  conditions,  as  applied  to  gases,  one  under- 
stands temperature,  o°  C.  or  32°  F.,  and  atmospheric  pressure  760  m.m., 
or  29.922  inches  of  mercury. 

To  reduce,  therefore,  a  body  of  air  to  these  standard  conditions, 
the  two  corrections  pointed  out  in  the  above  paragraphs  are  made 
together,  as  follows:  We  found  that  for  each  increase  of  i°  C.  in  the 
temperature  of  a  gas  its  volume  was  increased  0.003667,  and  for  an 
increase  of  /°  C.  in  temperature  its  volume  would  be  expressed  as 

v  _[_  (o.  003667.  /°) 

To  find,  therefore,  what  the  observed  volume  of  a  gas  (z^)  at  the 
observed  temperature,  /°  C.,  would  be  when  reduced  to  o°  C.,  we  have 

v0  :v}  =  i  :  i  4-  (0.0036677°) 

and  not  an  inverse  proportion  as  in  the  case  of  the  pressure,  for,  as 
stated,  the  increase  in  volume  is  directly  proportionate  to  the  increase 
in  temperature;  hence 


(o.oo3667./°) 


50  PHYSICS    OF    THE    ATMOSPHERE. 

We  found  now  that  the  volume  of  a  gas  reduced  from  the  observed 
conditions  of  pressure  to  the  standard  conditions  was  expressed  by  the 
formula: 

v  .  b 

V,t    =•    —  7  — 
70O 

this  without  taking  the  temperature  into  consideration. 

It  is  more  convenient  to  combine  the  two  formulae,  and  make 
both  corrections  at  once,  than  to  make  them  separately. 

The  result  of  combining  the  two  expressions  for  temp,  and  press- 
ure correction  with  a  single  formula  will  be, 


.0))       in  which 

v1  =  observed  volume  of  gas. 
p  —  observed  pressure  under  which  the  gas  exists. 
760  m.m.  =  normal  barometric  pressure. 
0.003667  =  co-efficient  of  expansion  for  air. 
t°  =  observed  temperature  at  which  the  gas  exists. 
#0  =  volume  of  gas  required  under  normal  conditions  of  temp. 
and  pressure. 

Example.  —  One  hundred  litres  of  air  exist  at  20°,  C,  and  720 
m.m.  barometric  pressure  (barometer  reduced  to  o°  C.,  see  below). 
What  will  be  the  volume  under  normal  conditions?  Substituting  these 
readings  into  the  above  formula,  we  find, 

100  X  720 

z;    =  —;  —  -  —  —  -.  —  —7-7  --  oT-y  =  88.26  litres  at  o°  C.,  and  760  m.m. 
760  (i  -f-  (0.003667.20  )  ) 

NOTE.  —  Where  the  English  measures  are  employed,  it  must  be  borne  in 
mind  that  the  normal  barometric  pressure  is  29.922  inches  of  mercury,  and 
the  co-efficient  of  expansion  for  air  is  0.00236  for  each  degree  Fahrenheit, 
above  32°.  These  quantities  must  therefore  be  substituted  for  those  given  in 
the  above  formula. 

Reduction  of  Barometric  Reading  to  o°  Temp.  —  In  considering 
atmospheric  pressure  as  indicated  by  the  height  of  the  mercurial 
column  of  the  barometer,  it  must  be  borne  in  mind  that  the  variations 
in  height  of  the  column  are  due,  not  alone  to  alterations  in  the  press- 
ure of  the  air,  but  to  a  small  extent  to  fluctuations  in  temperature 
also.  Mercury  follows  the  same  general  law  of  expansion  under  the 
influence  of  heat  as  do  other  bodies.  It  is  necessary,  therefore,  in 
order  to  determine  what  proportion  of  the  length  of  the  mercurial 
column  is  due  to  atmospheric  pressure  alone,  that  the  influence  of 


PHYSICS    OF    THE    ATMOSPHERE.  5  i 

temperature  be  eliminated,  or  rather,  corrected  for;  that  is,  the  observed 
reading  must  be  reduced  to  what  it  should  be,  if  the  existing  temper- 
ature were  o°  C.,  or  32°  F.  As  was  seen  in  the  case  of  air,  mercury  has 
a  constant  rate  of  expansion  —  for  each  degree  centigrade  this  co- 
efficient of  expansion  is  0.00018.  That  is,  with  an  increase  of  each 
degree  in  temperature  above  o°  C.,  the  expansion  of  the  column  of 
mercury  due  to  temperature  alone  is  0.00018  of  itself.  If,  therefore,  a 
column  of  mercury  whose  height  is  b  at  OQ  C.,  be  subjected  to  an  in- 
crease of  i  degree  in  temperature,  the  pressure  remaining  constant,  it 
will  no  longer  be  £,  but  b  -\-  (b  x  0.00018),  if  to  tQ  C.  temp,  then 
b  -j-  (  b  x  (0.00018.  /°)  ).  If,  therefore,  it  is  desired  to  give  an  ob- 
served reading  at  any  given  temperature  in  terms  of  o°  C.,  temperature 
corrections  must  be  made  for  the  expansion  due  to  the  heat  —  this 
expansion  must  be  subtracted  from  the  observed  height  of  the  column. 
If  the  observed  height  of  the  column  due  to  atmospheric  pressure 
and  temperature  together  be  represented  by  b  -f  (b  x  0.00018  X  t°), 
or,  which  is  the  same,  b  (i  -(-o.oooiS./0),  then  it  is  plain  that  if  the  pres- 
sure remains  constant,  the  height  of  this  column  under  the  influence 
of  no  temperature  above  o°  C.,  will  be  less  than  is  expressed  by  the 
above  formula.  This  amount  of  shortening  will  be  expressed  by  the 
portion  of  the  formula  (b  x  o.oooiS./0),  therefore,  the  correction  for 
temperatures  above  o°  C.  lessens  the  length  of  the  observed  column, 
whereas,  for  temperatures  below  o°  C.,  they  increase  its  length.  The 
corrections  for  temperatures  above  zero  are  made  by  this  formula  : 


0  ~~  i  +  (0.00018  X  /°) 

£0  =  Height  of  mercurial  column  at  o°  C. 

^o  =2  Height  of   mercurial   column   at   existing  temperature   as 

shown  by  attached  thermometer. 

f°  =  temperature  indicated  by  attached  thermometer. 
0.00018  =  co-efficient  of  expansion  of  mercury. 

Example.  —  Observed  height  of  barometer,  750  m.m. 

Temp,  of  attached  thermometer,  20°  C. 

What  should  the  height  of  the  column  be  when  reduced  to  o°  C 

750 

'     m'm- 


i  +  (0.00018  X  20) 

Strictly  speaking,  there  are  several  other  corrections  which  should 
be  made  before  the  absolute  length  of  the  mercurial  column  due  to 
atmospheric  pressure  alone  can  be  determined.  These  are  corrections 


52  PHYSICS    OF    THE    ATMOSPHERE. 

for  index  error  of  instrument,  capacity  corrections,  and  capillarity 
correction,  but  for  our  purposes  the  reduction  to  o°  C.,  as  given  above, 
will  suffice. 

NOTE. — Where  the  Fahrenheit  scale  is  employed  it  must  be  remembered 
that  for  each  degree  on  this  scale,  above  32°,  the  co-efficient  of  expansion 
of  mercury  is  o.oooiooi.  Also,  that  the  freezing  point  in  this  scale  is  at 
32°,  and  not  at  o°,  as  in  the  case  of  the  centigrade.  We  must,  therefore, 
remember  in  reducing  our  mercurial  column  to  the  normal  conditions  of  tem- 
perature, that  in  the  one  scale,  centigrade,  this  point  is  o°,  and  in  the  other, 
Fahrenheit,  it  is  32°.  In  the  case  of  the  latter,  therefore,  32  must  be  sub- 
tracted from  the  reading  of  the  attached  thermometer.  Substituting  then 
these  quantities  for  those  found  in  the  formula  given  we  should  have 


82  -  i  +  (o.oooiooi  X  (/  -  32)) 

Moisture  in  the  Atmosphere. — As  has  been  said,  the  amount  of 
moisture  which  the  air  is  capable  of  holding  in  the  form  of  invisible 
vapor  is  dependent  upon  the  temperature  of  the  air  and  upon  the 
opportunities  presented  to  it  for  taking  up  water. 

The  presence  of  water  in  the  invisible  form  of  vapor  may  easily 
be  demonstrated  by  bringing  the  air  in  contact  with  some  body  of 
a  much  lower  temperature.  The  moisture  will  become  condensed 
upon  the  sides  of  the  vessel  in  the  form  of  visible  water  ;  this  is  the 
phenomenon  known  commonly  as  "  sweating  "  which  one  sees  upon 
the  outside  of  ice  pitchers.  It  is  the  condensation  of  the  water- 
vapor  from  the  air  in  immediate  contact  with  the  vessel. 

The  air  is  rarely  saturated  with  moisture,  that  is,  it  rarely  contains 
so  much  in  the  form  of  vapor  as  to  render  it  impossible  for  a  little  more 
to  be  taken  up.  A  simple  experiment  will  prove  this.  If  in  an  ordi- 
nary room  one  evaporates  a  basin  of  water,  there  will  be  but  little 
apparent  alteration  in  the  air  of  the  room,  still  it  has  taken  up  in  the 
form  of  invisible  vapor  all  of  the  water  which  was  before  in  the  vessel. 
This  water  may  be  recovered  by  reducing  the  temperature  of  the 
air  of  the  room  to  a  point  at  which  the  invisible  vapor  becomes  con- 
densed. 

By  the  addition  of  water-vapor  to  dry  air  the  volume  of  the  latter 
becomes  increased.  If  the  weight  of  the  original  volume  of  dry  air  be 
known  it  will  now  be  found  that  for  the  same  volume  the  addition  of 
water-vapor  has  lessened  the  weight  and  that  this  diminution  in  weight 
is  proportionate  to  the  amount  of  vapor  added. 

In  other  words,  dry  air  is  of  a  much  higher  specific  gravity  than 
moist  air. 


PHYSICS    OF    THE    ATMOSPHERE.  53 

If  three  vessels  of  known  weight  and  of  exactly  the  same  volume 
"be  filled,  the  first  with  absolutely  dry  air,  the  second  with  air  in  which 
some  moisture  is  present,  and  the  third  with  water  vapor  alone,  it  will 
6e  found  that  the  weight  of  the  contents  of  No.  i  will  be  heaviest, 
that  of  No.  3  lightest,  while  No.  2  will  occupy  a  position  between  the 
two,  its  relations  to  No.  i  or  No.  3  being  dependent  upon  the  propor- 
tion of  vapor  which  is  substituted  for  the  dry  air. 

The  ratio  between  the  weights  of  equal  volumes  of  dry  air  and  of 
water  vapor  at  the  temperature  of  10°  C.  (50°  F.),  is  as  133  to  i  ;  that 
is  to  say,  at  this  temperature,  dry  air  is  133  times  as  heavy  as  water 
vapor,  volume  for  volume. 

A  litre  of  dry  air  at  o°  C.  and  760  m.m.  pressure  weighs  1.293 
grams. 

A  cubic  foot  of  dry  air  at  32°  F.  and  29.922  inches  pressure  weighs 
0.80728  pounds. 

When  water-vapor  mixes  with  dry  air  the  volume  of  the  latter  is 
augmented  ;  the  weight  of  a  cubic  foot  of  dry  air  at  60°  F.  is  536.28 
grains ;  and  that  of  a  cubic  foot  of  vapor  at  the  same  temperature  is 
5.77  grains  ;  the  two  together  would  weigh  542.05  grains,  but  owing  to 
the  increase  in  volume  of  the  air  which  the  addition  of  water  vapor 
causes  we  find  a  cubic  foot  of  saturated  air  at  60°  F.  to  weigh  only 
532.84  grains.  From  what  has  been  said  it  is  plain  that  the  addition 
of  water-vapor  to  air  renders  it  lighter,  and  that  this  diminution  in 
weight  is  proportionate  to  the  temperature,  for,  as  said,  the  higher  the 
temperature  of  the  air  the  greater  the  amount  of  vapor  that  it  can 
take  up. 

Tension  of  Vapor. — Vapor  as  it  exists  in  the  air  exerts  a  force 
which  is  also  dependent  upon  temperature.  This  elastic  force,  acting 
in  all  directions,  is  known  as  the  tension  of  the  vapor.  It  is  capable  of 
doing  work.  It  will  support  a  column  of  mercury,  the  height  of  which 
will  depend  upon  the  temperature  under  which  the  vapor  exists.  By 
virtue  of  this  tension  vapors  have  always  a  tendency  to  escape  or  press 
out  from  the  vessels  containing  them.  If  with  a  properly  constructed 
apparatus  a  volume  of  water-vapor  be  subjected  to  varying  tempera- 
tures, it  will  be  seen  that  the  height  of  the  mercurial  column  which  it 
supports,  as  shown  by  the  manometer,  will  rise  as  the  temperature 
rises,  and  fall  as  the  temperature  falls. 

Experiment  has  shown  a  certain  regularity  in  this  increase  of  ten- 
sion with  increase  of  temperature.  The  following  table  gives  the 
height  of  a  mercurial  column  supported  by  aqueous  vapor  under  dif- 
ferent temperatures: 


54 


PHYSICS    OF    THE    ATMOSPHERE. 

TENSION  OF  AQUEOUS  VAPOR  IN  m.m.  OF  MERCURY 


/°c. 

m.m. 

t°C. 

m.m. 

t°C. 

m.m. 

t°C. 

m.m. 

0 

4.6 

10 

9-1 

20 

17.4 

30 

31-5 

I 

4.9 

ii 

9-8 

21 

18.5 

40 

54-9 

2 

5-3 

12 

10.4 

22 

19.6 

50 

92.0 

3 

5-7 

13 

II.  I 

23 

20.9 

60 

148.9 

4 

6.1 

14 

ii.  9 

24 

22.2 

70 

233-3 

5 

6-5 

15 

12.7 

25 

23.5 

80 

354-9 

6 

7.0 

16 

13-5 

26 

25.0 

90 

525.5 

7 

7-5 

17 

14.4 

27 

26.5 

100 

760.0 

8 

8.0 

18 

1C  -J 

28 

28  I 

q 

8.5 

ig 

16  3 

29 

2Q  7 

From  the  table  a  gradual  increase  in  the  tension  will  be  seen  to 
co-exist  with  a  corresponding  rise  in  temperature  until  the  boiling  point 
of  water  (100°  C.)  is  reached,  when  it  exactly  equals  the  normal  press- 
ure of  the  atmosphere. 

Without  opening  the  discussion  as  to  the  part  played  by  aqueous 
vapor  in  influencing  general  atmospheric  pressure,  we  may  neverthe- 
less see  that  in  closed  spaces  its  presence  means  the  absence  of  just  so 
much  dry  air  which  it  displaces,  and  as  dry  air  is  heavier  than  water 
vapor,  it  is  easy  to  see  that  with  an  increase  in  the  amount  of  vapor 
present  in  these  spaces,  we  have  a  corresponding  diminution  in  the 
specific  gravity  of  the  contained  air. 

Effusion  of  Gases. — Effusion  is  the  term  applied  to  the  passage  of 
a  gas  from  one  space  into  another  space  occupied  by  the  same  gas. 
It  can  only  occur  when  the  pressure  in  the  one  space  is  greater  than 
that  in  the  other. 

In  the  strictest  sense,  the  term  as  employed  by  physicists,  refers 
to  the  flowing  of  a  gas  from  an  inclosed  space  into  vacuum  through  a 
minute  aperture  not  more  than  0.013  m.m.  in  diameter  in  a  very  thin 
plate  of  metal  or  glass. 

In  our  studies  the  term  will  be  employed  to  express  the  efflux  of 
gases  of  different  densities  through  larger  openings.  The  velocity  of 
the  efflux  of  a  gas  of  known  density  under  known  pressure  into  vacuum 
is  expressed  by  the  formula, 

v  =  V  2  gh, 

in  which  h  represents  the  pressure  under  which  the  gas  flows  expressed 
in  terms  of  the  height  of  a  column  of  gas  which  would  exert  the  same 
pressure  as  does  the  effluent  gas.  Thus,  if  air  under  normal  pressure 
flows  into  vacuum,  this  pressure  is  equivalent  to  that  exerted  by  a 


PHYSICS    OF    THE    ATMOSPHERE. 


55 


column  of  air  capable  of  sustaining  the  weight  of  a  column  of  mercury 
760  m.m.  high.  As  mercury  is  about  10,500  times  as  dense  as  air  an 
equivalent  column  of  air  would  be  760  X  10,500  =  7,980  meters.  The 
velocity  then  with  which  air  under  ordinary  atmospheric  pressure 
would  flow  into  vacuum  would  be 


v—          9  g   7,980  =  395.5  meters  per  second. 

(9.8  meters,  or  32  feet,  represent  the  accelerative  effect  of  gravity). 
This,  however,  would  be  only  for  the  first  second  of  time,  for  after  this 
there  would  be  an  accumulation  in  what  had  been  vacuum,  and  hence 
the  difference  in  pressure  between  the  air  in  the  two  spaces  will  gradu- 
ally diminish.  With  this  diminution  in  difference  a  lessening  of  the 
velocity  of  efHux  ensues,  until  finally,  when  the  pressure  in  both  spaces 
are  equal,  no  movement  whatever  occurs.  If  during  the  efflux  the 
pressure  in  both  spaces  be  measured  at  given  intervals,  and  expressed 
by  h.  /jj,  etc.,  the  velocity  of  efflux  at  each  of  these  intervals  may  be 
calculated  by  the  formula: 

V   =    ^2.  g.    (A-^) 

h  =  pressure  under  which  the  gas  is  flowing. 

hl  =  accumulating  pressure  in  what  was  originally  vacuum. 

In  our  work  the  second  formula  is  the  one  which  will  be  em- 
ployed in  calculating  the  rate  of  efflux  between  gases  of  different  den- 
sities. We  shall  never  meet  the  conditions  in  which  the  first  may  be 
employed. 

As  an  illustration  of  its  application  the  following  problem  may  be 
cited. 


H 


FIG. 


Imagine  aB  to  be  a  vertical  canal  open  above,  a  chimney  for 
example,  of  the  height  ZTand  of  equal  diameter  throughout.     So  long 


56  PHYSICS    OF    THE    ATMOSPHERE. 

as  the  air  in  aB  is  of  the  same  density  and  specific  gravity  as  the  sur- 
rounding air  no  motion  occurs.  So  soon  as  alterations  in  the  relative 
densities  of  the  two  bodies  of  air  occur,  motion  begins.  Such  altera- 
tions may  be  caused  by  elevation  in  the  temperature  of  the  one  body  of 
air  over  that  of  the  other.  Suppose  the  temperature  of  the  outer  air  to 
be  lower  than  that  in  the  canal  (T)  and  imagine  aB  to  be  continued 
into  a  canal  cD  thus  forming  the  imaginary  U  tube,  aB  cD.  Now 
the  imaginary  arm  of  the  tube  represented  by  cD  is  assumed  to  be 
of  the  same  size  throughout  as  is  aB.  It  differs  from  aB  only  in 
the  temperature  of  the  air  contained  in  it,  which  is  lower  and  will  be 
represented  by  t°.  We  shall  now  have  a  U  tube  in  the  one  arm  of 
which  the  air  is  of  a  higher  specific  gravity  than  that  in  the  other  arm. 
For,  as  we  have  shown,  with  an  increase  in  the  temperature  of  air  there 
is  a  corresponding  decrease  in  its  density  and  specific  gravity.  In  the 
case  in  point  there  must,  of  necessity,  be  an  effort  at  the  establishment  of 
equilibrium  and  the  denser  air  in  the  arm  cD  at  the  temperature  /°  will 
sink  at  the  same  rate  that  the  rarer,  lighter  air  in  the  arm  aB  at  the 
temperature  T°  ascends. 

It  is  here  that  we  must  employ  the  formula,  v  =  /y/2  <r  h   for 

/         v^  \ 
obtaining  the  height  (h  =  —  J   through  which  the  bodies  of  air  fall. 

The  distance  through  which  the  denser  air  in  cD  falls  is  the  differ- 
ence between  the  height  of  an  imaginary  column  of  air  of  the  weight 
of  cD  at  the  temperature  T,  and  the  actual  measured  height  of  the 
tube  aB,  as  expressed  by  H.  In  order  to  obtain  this  difference  it  is 
necessary  to  convert  the  two  columns  of  air  in  aB  and  cD  into  col- 
umns of  equal  weight,  but  of  densities  expressed  at  the  temperature  of 
o°  C.  They  will,  therefore,  be  of  different  height.  For  as  the  diame- 
ters of  the  tube  or  chimney  aB  and  the  imaginary  chimney  cD  are 
constant,  the  alterations  in  volume  which  will  result,  when  their  air  is 
reduced  to  the  condition  of  o°  C.,  must  have  its  expression  in  the 
lessening  of  the  height  of  each  column. 

The  height  of  aB  at  TQ  temperature,  when  reduced  to  o°,  is 

H 

i  +  «.  T 

and  that  of  cD  at  the  temperature  /Q  is 

H 

I  +  a.  / 
^0,  the  height  of  the  pressing  column  of  air  reduced  to  o°  C,  is  then 

H  H 

0     "  i  -f-  a.  t        l+a.T 


PHYSICS    OF    THE    ATMOSPHERE.  57 

If  now  it  is  desired  to  convert  this  column  of  air  into  one  of  equal 
weight,  but  of  the  higher  temperature  Ty  then  will  its  height  h  be 
expressed  by  //  =  /i0  (t  -f  <r.  T)>  or  substituting  the  value  of  7/0  just 
found,  we  shall  have 

//  =  (i  -f  «.  T 


and  since  h  —  —  then 


i!.  =  (i  -f-  a  T)  (  __  L_ 

' 


2g  Vl    -f   ".   /  x    +   « 

and  r  =  ,4/ocr     /T  -l-  cr  T' 


4-  «/         i-.+.a' 

Throughout  this  formula,  which  may  be  employed  in  calculating 
the  rate  of  flow  or  draught  with  chimneys,  etc.,  it  will  be  remembered 
that 

v  =  velocity  of  flow. 

g  =  accelerating  effect  of  gravity,  9.8  meters  per  second. 

T  =  higher  temperature  in  chimney. 

/  =  lower  temperature  of  outside  air. 

H  =  height  of  chimney. 

a  —  co-efficient  of  expansion  of  air. 

It  must  be  borne  in  mind  that  the  formula  as  it  stands  is  strictly 
theoretical,  and  could  only  be  employed  in  practice  after  certain  cor- 
rections for  friction,  curves  and  alterations  in  calibre  of  the  tubes  had 
been  made.  These  corrections  will  be  introduced  in  a  later  chapter 

In  addition  to  the  movement  set  up  in  connecting  bodies  of  air  of 
different  densities,  we  shall  also  find  a  constant  tendency  toward  effu- 
sion between  such  bodies,  even  though  they  may  be  apparently 
separated  the  one  from  the  other.  In  this  case,  the  current  is  not  set 
in  motion  through  free  openings  in  tubes  or  shafts,  as  in  the  case  cited, 
but  through  the  capillary  tubes  or  pores  in  the  separating  medium. 

If  two  bodies  of  air  of  different  temperatures  are  separated  the  one 
from  the  other  by  a  permeable  partition,  there  is  a  constant  tendency 
toward  the  establishment  of  a  current  from  the  cooler,  denser,  toward 
the  warmer,  rarer  body,  and  vice  versa. 

By  a  careful  study  of  this  phenomenon,  it  is  seen  that  if  the  sep- 
arating medium  be  an  enclosure  with  six  sides,  a  hollow  cube,  for 
instance,  that  these  currents  will  be  established  according  to  certain 
definite  and  constant  laws.  It  is  seen  that  on  the  vertical  sides  of 


PHYSICS    OF    THE    ATMOSPHERE. 


the  cube  the  direction  of  the  current  is  not  the  same  for  each   and 
every  point. 

Supposing  the  cube  to  contain  the  warmer,  less  dense  volume  of 
air,  it  will  be  seen  that  the  direction  of  the  current  becomes  reversed 
as  we  pass  from  the  highest  to  the  lowest  levels  of  each  lateral  wall. 
At  the  highest  elevation  the  stream  will  be  most  pronounced  from 
within  outward,  gradually  diminishing  as  we  near  the  center,  where 
the  so-called  neutral  zone,  through  which  there  is  no  appreciable  efflux, 
is  found.  Passing  below  this,  a  current,  the  reverse  of  the  outward 
flow,  is  met.  It  increases  in  intensity  in  practically  the  same  progres- 
sion as  the  outward  current  diminished  until  we  reach  the  lowest  level 
where  it  is  greatest,  and  will  be  found  to  correspond  in  intensity 
(in  homogeneous  partitions)  with  the  most  elevated  of  the  outgoing 
streams. 


w 


Jf- 


Warm 


'CoM 


-JV 


NN  —  neutral  zone. 


FIG.  4. 
w  =  warm  outflowing  air. 


c  =  cold  inflowing  air. 


Figure  4  represents  the  phenomenon  diagrammatically.  The  figure 
is  a  vertical  section  through  such  a  cube,  the  six  sides  of  which  are  of 
homogeneous  material  and  the  air  within  the  cube  of  higher  tempera- 
ture than  that  surrounding  it. 

From  the  figure  it  may  be  seen  that  under  the  conditions  cited  the 
strongest  expressions  of  out  and  inflow  are  represented  by  the  arrows 
w  and  c  at  the  highest  and  lowest  levels,  respectively,  of  the  lateral 
sides  of  the  cube  ;  and  a  gradual  diminution  toward  the  central, 
"neutral  zone"  occurs  in  both  cases. 

Over  the  horizontal  faces  of  the  cube,  top  and  bottom,  the  intensity 
of  efflux  as  represented  by  the  arrows  for  the  cold  air  from  without  in, 
and  for  the  warm  from  within  out,  is  everywhere  equal. 


PHYSICS    OF    THE    ATMOSPHERE.  59 

What  now  is  the  explanation  of  this  phenemenon  ?  As  has  been 
said,  the  tendency  for  warmed  air  is  to  expand  and  escape  from  the 
vessel  containing  it.  It  has  also  been  said  that  warm  air  is  of  a  lower 
specific  gravity  than  cold  air — it  has  therefore  a  tendency  to  ascend. 
Now  for  the  case  under  consideration  we  find  that  the  point  of  greatest 
density  for  both  the  warmed  air  within  and  the  cold  air  without  our 
cube  is  at  the  floor  level  and  that  of  least  density  at  the  level  of  the 
ceiling.  In  both  cases  however,  the  cold  outer  air  is  denser  than  the 
warm  inner  air  and  consequently  there  should  be  a  tendency  over  the 
whole  outer  side  of  the  separating  partition  for  the  colder  air  to  rush 
in  toward  the  warmer  air;  but  this  tendency  is  overbalanced  in  part  by 
the  low  specific  gravity  and  tension  which  the  inner  air  has  acquired  by 
its  elevation  in  temperature  ;  so  that  it  presses  outward  on  all  sides  of 
the  vessel  containing  it. 

Our  body  of  warmed  air  of  low  specific  gravity  surrounded  by  the 
mass  of  cooler  air  of  greater  density  has  been  aptly  likened  to  a  mass 
of  solid  matter  immersed  in  a  fluid  of  higher  specific  gravity — a  block 
of  wood  immersed  in  water,  for  example.  It  experiences  its  greatest 
pressure  from  the  surrounding  denser  fluid  at  its  point  of  lowest  level, 
which  pressure  diminishes  as  we  approach  the  point  of  highest  level. 
In  the  case  then  of  our  warmed  air  enclosed  in  a  space  with  upper  and 
lower  openings — a  room,  for  example — we  see  over  the  floor  and  lower 
parts  of  each  side  the  pressure  from  the  denser,  cooler  air  is  inward, 
toward  the  warmer  body  of  lower  specific  gravity.  As  the  denser  air 
enters  through  the  openings  into  the  cube  (the  source  of  heat  in  the 
cube  remaining  constant)  it  in  turn  becomes  heated  and  ascends. 
Some  of  the  warmed  air  that  was  in  the  cube  must  in  turn  be  pressed 
out  and  by  proper  means  we  find  that  just  at  the  same  rate  as  the 
cooler,  denser  air  enters  at  the  bottom  and  lower  parts  of  the  sides, 
the  warmer,  rarer  air,  of  less  specific  gravity  and  higher  tension, 
is  forced  out  through  the  ceiling  and  upper  parts  of  the  sides  of  the 
cube. 

By  the  employment  of  a  delicate  differential  manometer  we  shall 
find  that  the  point  of  greatest  pressure  in  the  outer  column  of  cold  air 
is  at  the  floor  level  of  our  cube,  and  that  the  pressure  gradually  dimin- 
ishes as  we  approach  the  ceiling.  For  the  warm  inner  air  the  point  of 
least  tension  will  be  found  at  the  floor,  and  that  of  the  highest  tension 
at  the  ceiling. 

The  result  of  these  conditions  is  the  establishment  of  two  currents, 
as  shewn  in  Fig.  4 — a  cold  inflowing  current,  greatest  in  intensity  at 
the  floor  level  and  diminishing  as  we  ascend,  and  a  warm  outflowing 


6o 


PHYSICS    OF    THE    ATMOSPHERE. 


current,  greatest  in  intensity  at  the  ceiling  level  and  diminishing  as  we 
descend. 

Figure  5  also  illustrates  what  takes  place  under  these  conditions. 


Such  an  exchange  between  bodies  of  air  of  different  temperatures 
is  constantly  in  progress.  It  is  what  occurs  in  the  so-called  "  natural 
ventilation,"  and  it  forms  the  fundamental  principle  upon  which  nearly 
all  artificial  contrivances  for  the  renewal  of  air  in  apartments  are  based. 

In  the  chapter  upon  forces  concerned  in  ventilation  reference  will 
again  be  made  to  this  subject  in  its  practical  application. 

NOTE. — This  phenomenon  may  be  satisfactorily  demonstrated  by  the 
employment  of  a  very  inexpensive  model.  A  wooden  frame  of  about  8  feet 
high  by  4  feet  by  2  feet,  covered  with  ordinary  muslin,  has  on  its  long 
face  two  openings,  each  4"  x  6"  in  size — the  one  just  above  the  floor,  the  other 
just  below  the  ceiling — these  openings  to  be  closed  by  loosely  swinging  paper 
flaps.  If  now  the  interior  of  our  model  be  heated  by  a  Bunsen  burner,  or  lamp 
of  any  description,  it  will  be  seen  that  the  lower  flap  will  be  deflected  inward 
and  the  upper  outward.  A  series  of  flaps  down  the  median  line,  each  situated 
about  4  inches  from  the  one  above  it,^will  also  demonstrate  the  diminution  in 
the  intensity  of  each  stream  as  we  approach  the  median  line,  "  neutral  zone." 


CHAPTER  IV. 

CARBONIC     ACID. 

THE  proportion  of  carbonic  acid  in  the  atmosphere  is  considered  to 
be  of  such  biological  and  sanitary  importance  that  it  is  deemed 
advisable  to  devote  a  separate  chapter  to  the  subject. 

In  the  studies  of  the  chemistry  of  the  air  the  points  that  have  been 
considered  worthy  of  determination,  in  so  far  at  least  as  the  proportion 
of  carbonic  acid  is  concerned,  are  :  Is  it  possible  to  speak  of  a  con- 
stant mean  proportion  of  this  gas  for  all  places  on  the  earth's  surface  ? 
Does  the  air  over  the  land  differ  in  the  proportion  of  this  gas  contained 
in  it  from  that  over  the  sea?  Is  the  proportion  of  carbonic  acid  in  the 
air  of  cities  greater  than  that  in  the  air  of  the  open  fields  of  the 
country  ?  Does  the  proportion  of  this  gas  remain  constant  for  the  same 
place  under  varying  conditions — for  day  and  night ;  for  winds  from  all 
directions  ;  for  fair  and  foul  weather,  etc.  ?  Is  the  proportion  of  this 
gas  seen  to  differ  at  different  altitudes ?  And  is  the  relatively  lower 
proportion  of  CO2  in  the  air,  which  experiments  of  to-day  reveal,  due 
to  improvements  in  methods  or  to  differences  in  the  rate  of  produc- 
tion ? 

The  experiments  which  have  been  made  with  the  object  of  answer- 
ing these  questions  have  been  many  in  number,  and  have  not  all  been 
made  by  the  same  methods  of  work,  or  by  the  same  individuals.  A 
glance  over  the  history  of  the  subject  will  suffice  to  show  that  the  results 
which  have  been  obtained  in  recent  years  are  on  the  whole  much  lower 
than  those  obtained  by  the  earlier  experimenters.  It  seems  reasonable  to 
attribute  these  differences  rather  to  increased  accuracy  in  the  methods 
of  analysis  than  to  any  diminution  in  the  proportion  of  this  gas  in  the 
air,  for  during  the  ninety  years  which  have  elapsed  since  de  Saussure 
first  published  the  results  of  his  quantitative  analysis  of  the  air,  but 
little  change  in  the  natural  and  artificial  processes  incidental  to  life 
which  would  tend  to  lessen  the  proportion  of  this  gas  existing  in  the 
air,  could  have  occurred. 

In  the  accompanying  table  (Table  I.)  will  be  found,  grouped 
together  in  the  order  in  which  they  were  published,  the  results  of  the 


62 


CARBONIC    ACID. 


TABLE  I. 

Volumes  of  Carbonic  Acid  in  10,000  Vols.  of  Air  as  Found  by  Different 
Observers  and  at  Different  Places  since  the   Time  of  de  Saussure. 


Observer. 

Place. 

Date. 

Vols.  of  CO2 
in  10,000  Vols. 
of  Air. 

Geneva     

1809  15 

'Phenard 

Paris                         .    .  . 

1813 

De  Saussure 

Chambeisy             .        ... 

1816  28 

3.910 

De  Sa.ussure 

Chambeisy  . 

1827  ^o 

4.9°° 

Brunner 

Bern     .           

1832 

4ifin 

Tissandier  

Balloon  ascension,  alt.  2920  ft. 

2    140 

Boussingault         

"  3281  ft. 
Paris  '      

iS^Q   AO 

3.000 

Marchand     

Halle  

I  SAC 

Levy 

Atlantic  Ocean     .     .   . 

1847 

A  &  H  Schlagentweit 

Karuthen   . 

iSc-; 

Sfinn 

Switzerland 

Gilm 

Innsbruck  .            ....         .    . 

lS^.7 

Pettenkofer    .  .  . 

Munich  

1858 

.  150 

Regnault             

Paris       

i8cQ 

Schulze    

Rostock  

1863-64 

-5   6/10 

Schulze 

Rostock 

1868   71 

Thorpe 

S   America  (at  Para). 

1866 

3280 

Thorpe  

Irish  Sea  and  Atlantic  Ocean. 

1865-66 

3  ooo 

Storer  and  Pearson 

Boston            .  .       

1871 

38CA 

Hill 

Cambridge  .  .           

1871 

3<3QO 

Smith 

London              .             

1872 

3J.QO 

Heuneberg 

Weende            .                  ... 

1872 

3  200 

Risler 

Calives                    

1872—7'} 

3  ooo 

Truchot.  . 

Clermont-Ferrand  

187^ 

-7      J-7Q 

Truchot  

Puyde  Dome  (alt  4,774ft.).. 

2    O1O 

Truchot  

Pic  de  Sancy  (alt.  6,181  ft.).. 

I     720 

Reiset  

Montsouris  

1873-80 

2  .962 

Farsky 

Tabor  (Bohemia).         .     .    . 

1874—  75 

•2     A'iQ 

Fittbogen   and   Haes- 
selbarth  

Dwhne.            .  .           

l87A    7C 

Muir  

Andrassan  (Scotland)  

1876 

Claesson  

Lund  

1876 

2     8OO 

Hesse  

Munich  

l877 

3OQO 

Levy 

Montsouris 

1877  8^ 

Wolff  hugel 

Munich 

1870 

o    7^0 

Macagno  .  .  . 

Palermo 

-870 

3QOO 

Armstrong.  .  . 

Grasmere 

1880 

2    960 

Fodor  

Budapest 

1  88  1 

38QO 

Fodor  ..     . 

Klausenbiirg 

3  800 

Muntz  &  Aubin  
Mttntz  &  Aubin     .  .  . 

Orange  Bay  (Cape  Horn).  .  .  . 
S.  Atlantic  Ocean.  

1881-84 

2.560 
2    680 

Dumas  

Paris                        

1882 

2  .  800—3  5°° 

Heine  

Giessen                             

1882 

2.620 

Reichardt  

Jena  

1882-84 

3.000 

Ebermeyer 

Bavarian  Highlands 

1881-84 

1    2OO 

Blochmann               .  . 

Konigsberg 

1885 

3  ooo 

Spring  and  Roland..  .  . 

Luttich 

1885 

3.300 

CARBONIC    ACID. 
TABLE  I.  (Continued.} 


Observer. 

Place. 

Date. 

Vols  ofC02 
in  10.000  Vols. 
of  Air. 

Carnelley  and  Mackey. 

Dundee  

1886 

3I7C 

Carnelley  and  Mackey. 

Perth  

1886 

3  100 

Feldtz 

Dorpat 

1887 

2    660 

Carnelley  and  Wilson  . 

Scotch  Moorlands  

1887-88 

3    9O 

Uffelmann  

Rostock  ....         

1888 

•?  ci 

Heimann 

Dorpat     

1888 

2.690 

Frev 

Dorpat 

1880 

2    62O 

L  1C>  
Roster 

Florence 

1889 

3    I4O 

Abbott 

Baltimore    .             

1889 

3.750 

more  prominent  experiments  which  have  been  made  from  the  time  of 
de  Saussure  to  the  present.  And,  as  stated,  the  tendency  throughout 
the  later  experiments  is  toward  a  smaller  mean  proportion  of  atmos- 
pheric carbonic  acid  than  was  found  by  the  earlier  observers.  It  will 
be  seen,  moreover,  that  since  the  introduction  by  von  Pettenkofer  in 
1858,  of  the  method  of  analysis  which  bears  his  name,  that  the  results 
of  these  experiments  are  on  an  average  much  lower  than  the  mean  of 
those  observations  published  prior  to  that  date,  and  that  the  range  of 
fluctuation  in  the  results  has  been  considerably  diminished. 

By  dividing  the  experiments  which  have  been  made  since  the 
experiments  of  de  Saussure  into  groups  and  taking  their  mean, 
a  better  idea  of  the  diminution  in  the  results  obtained  may  be 
formed.  In  dealing  with  the  series  of  results  in  this  way,  it  has 
been  deemed  advisable  to  omit  from  the  results  from  which  the 
means  are  calculated  the  analyses  of  Tissandier  and  those  of  Truchot 
which  were  made  at  high  altitudes,  likewise  the  experiments  of 
Kidder  in  Washington,  because  of  their  exceptionally  high  results, 
which  must  certainly  have  arisen  from  some  strictly  local  causes. 


Period      I. — From  de  Saussure  to  Pettenkofer,  inclusive, 
Period    II. — From  Regnault  to  Reiset,  inclusive, 
Period  III. — From  Farsky  to  Reichardt,  inclusive, 
Period   IV. — From  Ebermeyer  to  Roster,  inclusive, 
Mean  since  1858  (introduction  of  Pettenkofer's  method), 


=  4-852 

=  3.392 

=  3.218 

=  3-nS 

=  3 . 243 


While  it  is  probable  that  certain  local  conditions  may  play  a 
part  in  causing  differences  in  the  proportion  of  carbonic  acid  found 
at  different  places,  still  it  must  be  borne  in  mind  that  an  equally  potent 
factor  in  producing  this  difference  in  results  is  the  method  which  is 


64  CARBONIC    ACID. 

employed  in  making  the  analyses.  Prior  to  the  introduction  by 
von  Pettenkofer,  in  1858,  of  the  method  which  bears  his  name  and  which 
is  now  so  generally  practised,  many  of  the  analyses  were  conducted  in 
a  way  that  could  hardly  lay  claim  to  a  very  high  degree  of  accuracy. 
For  example,  Levy's  experiments  in  1847  were  made  by  passing 
a  measured  quantity  of  air  through  glass  tubes,  containing  pumice 
stone,  which  had  been  soaked  in  potassium  hydroxide.  The  CO2  was 
fixed  by  the  alkaline  base.  These  tubes  were  then  sealed,  and  after  18 
to  20  months  their  contents  were  subjected  to  the  action  of  acid;  this 
liberated  the  carbonic  acid  which  was  collected,  and  its  volume  meas- 
ured eudiometrically  by  the  method  of  Regnault.  In  speaking  of  the 
possible  error  through  the  employment  of  this  method,  Dr.  Frankland 
(Jour.  Chem.  Soc.,  London,  Vol.  VI.,  p.  199)  says:  "A  variation  in 
volume  which  would  be  indicated  by  only  a  small  numerical  expression 
in  the  Regnault-Reiset  apparatus  would  be  considerable  had  it  ap- 
peared in  the  more  exact  analytical  methods  of  gas  analysis  as  recom- 
mended by  Bunsen."  Moreover,  Levy's  analyses  were  made  a  long 
time  after  the  air  had  been  passed  through  the  tubes;  in  some  instances 
as  much  as  18  to  20  months  having  expired,  and  though  he  had 
convinced  himself  that  during  this  time  air  confined  in  glass  tubes 
underwent  no  appreciable  change,  still  Regnault  has  subsequently 
demonstrated  the  error  of  this  opinion.  Regnault  has  shown  that  an 
accurate  estimate  of  the  proportion  of  carbonic  acid  originally  present 
in  air  which  had  been  contained  in  glass  tubes  for  a  long  time  cannot 
be  made  because  of  the  absorption  of  gases  by  the  glass. 

Such  sources  of  error  must  have  existed  in  many  of  the  analyses 
which  were  made  prior  to  our  more  exact  methods  of  to-day,  and  it  is 
only  reasonable  to  conclude  that  the  grounds  for  the  smaller  mean  pro- 
portion of  CO3  now  found  in  the  air  can,  at  least  in  part,  be  attributed 
to  correction  of  these  errors. 

By  tabulating  the  results  of  analyses  which  have  been  made  upon 
the  air  of  cities,  it  will  be  seen  that,  on  the  whole,  the  proportion  of 
carbonic  acid  is  higher  than  in  the  air  of  the  country,  and  that  its  range 
of  variation  is  much  greater.  These  differences  are  doubtless  due  in 
most  part  to  strictly  local  conditions.  In  cities  the  greater  activity  of 
life,  the  excess  of  artificial  processes  of  oxidation,  the  crowding  together 
of  a  larger  number  of  human  beings  and  animals  into  small  spaces,  and 
the  interference  with  free  circulation  and  diffusion  of  air  would  lead 
one  a  priori  to  anticipate  the  presence  of  a  larger  proportion  of  this  gas 
in  the  air  than  would  be  found  in  the  air  of  localities  in  which  these 
sources  of  production  were  diminished  or  absent.  Moreover,  in  cities 


CARBONIC    ACID.  6^ 

the  influence  of  plant  life  in  diminishing  the  proportion  of  this  gas  in 
the  air  is  very  much  less  than  in  the  rural  districts. 

In  the  accompanying  tables  are  compared  the  results  of  a  number 
of  analyses  which  have  been  made  upon  the  air  of  cities  and  that  of  the 

country. 

TABLE  II. 

CO2  in  the  Atmosphere — Analyses  of  Air  in  Cities. 


Observer. 

Place. 

CO»  in  10,000 
Vols.  of 
Air. 

Angus  Smith,  1872.  . 

Geneva  

4  68 

Chambeisy  

460 

« 

Madrid 

e    16 

« 

Streets  of  Manchester.         

4O'T 

i 

London.  .       

•3     gO 

« 

44       N.  and  N.  W.  winds 

A     A  A 

, 

"      S.     "     S.W.         '•     

A      -JQ 

t 

"       E.    "     S  E           ••    ... 

47C 

\ 

"       W.                          "     
At  different  towns  in  Scotland  (average).    .  .  . 
Glasgow  

4.12 

3.36 
5   O2 

Boussingault.  . 

Paris 

4  oo 

Wolffhiigel.     .     ... 

Munich   ...                        ... 

1    76 

Macagno.       .•. 

Palermo  

1  60 

Reiset  ,  

Paris  

1    O^ 

Fodor  

Klausenburg  

3  80 

Fodor  

Budapest  

3  89 

Farsky  

Tabor.     .    .  . 

-3     4-1 

Spring  and  Roland. 

Liittich  

a    a-j 

Hesse.            

Munich  

•2     •JO 

Blochmann  

Konigsberg  

3.OO 

Schulze  

Rostock  

2.92 

Uffelmann  . 

Rostock  (average  of  420  analyses) 

•J    ei 

Roster 

Florence  . 

3    14. 

Thenard  

Paris     . 

3.91 

De  Saussure  

Geneva.  ... 

4.15 

Abbott. 

Baltimore  (result  of  19  analyses  made  at  the 

Storer  and  Pearson.. 
Hill  

same  place  on  the  lawn  of  the  Johns  Hop- 
kins Hospital  during  December,  1889)  
Boston  —  Mean  of  21  analyses  made  in  streets. 
Cambridge,  Mass. 

3-75 
3.854 
1     7QO 

Heimann 

Dorpat  —  Mean  of  601  analyses  from  June  to 

September,  1888  

2   6Q 

Feldtz. 

Dorpat  —  Mean   for  February    March    April 

May,  1887  .    '  . 

2  66 

Frey.  .  . 

Dorpat  —  Mean  from  556  analyses 

2    62 

Kidder  (extract  from  the  Report  of  the  Surgeon-General  of  the 
Navy,  for  1880,  Washington,  Government  Printing  Office,  1882),  whose 
observations  were  made  upon  the  air  of  the  streets  of  Washington,  D. 
C.,  obtained  as  a  mean  of  96  analyses,  the  remarkably  high  proportion 


66 


CARBONIC    ACID 


of  7.66  parts  of  carbonic  acid  in  TO,OOO  parts  of  air.  Though  Kidder  is 
known  to  be  a  careful  observer,  still  his  results  are  of  such  an  unusual 
character  and  differ  so  materially  from  those  obtained  by  other  observ- 

TABLE   III, 

Analyses  by  Storer  <$"•»  Pearson,  Showing  the  Prbportion  of  Carbonic  Acid 
in  the  Atrfrom  the  Streets  of  Boston,  Mass.     Pettenkofer's  Method. 


<D'£ 

jz 

2% 

!_ 

%      • 

O  W 

Date 

1870. 

Time  of 
Day. 

c«O  a; 

li.1 

f| 

i! 

Locality. 

2>.b 

Remarks. 

»2" 

(•4     C 

H 

*o  o" 

**  O 

>  M 

March  17 

n.oo  A.  M. 

0 

3-5 

29.330 

1                                                f 

456o 

Cloudy.  Wind,N.W. 

-April      i 

8-45      " 

9.0 

30-372 

3-194 

Cleai.    Wind.  N.  E. 

i 

8-45      " 

9.0 

30.372 

3-894 

" 

"         8 

9.40      " 

13.0 

30.134 

3-988 

, 

"         8 

9.40      " 

13.0 

30-134 

4-449 

•• 

14         8 

9.40      " 

13.0 

30-134 

Newbury  St.,  near  In- 

4.218 

i 

\ 

"        13 

11.00        " 

14.0 

30.000 

stitute  of  Technology. 

3.798 

Cleai.    Wind,  N. 

"        13 

11.00        " 

14.0 

30.000 

4-435 

" 

'"        14 

2.35P.M. 

25.0 

30.016 

4-230 

Clear.    Wind,  S.  W. 

'"         14 

2-35      " 

25.0 

30.016 

4  292 

u 

'"        28 

2.20        •' 

28.0 

29.872 

4  999 

Cloudy.  Wind,S.W. 

"'        28 

2.20         " 

28.0 

29.872 

, 

4.903 

u                    ii             u 

May        3 

8.30         " 

14.0 

29.936 

Park  Street,  near  Tremont 

4-493 

Clear.    Wind,  N. 

12 
12 

2-45      " 

2.45    " 

22.0 
22.0 

29.852 
29-852 

I  Newbury  Street  •) 

3-394 

)  After  storm,  light 
(  clouds.  Wind,S.W. 

17 

10.45  A.  M. 

14.0 

30.170 

1                                               f 

2.905 

Cloudy.  Wind,  N.E. 

«          ,8 

4.05  P.  M. 

22.  0 

30.336 

}-  Public  Garden  •{ 

3.563 

Clear.    Wind,  S.  W. 

"          19 

10.50  A.  M. 

25.0 

30.244 

| 

2.969 

U                        11                     U 

"          30 

3.40  P.  M. 

2O.O 

30.264 

2.586 

S.  E. 

18 

3-15       " 

20-5 

30.336 

Zupola  of  State  House.   ... 
Clarendon  PI.,  nr.  Berkley 

3.139 

"             '•      S.  W. 

"          *9 

I   7O        *  ' 

28.0 

3O.2I2 

St  

o.  771 

(i                     tl                  il 

' 

3*  j  /  * 

Mean  of  21  Observations, 

3-854 

ers  at  the  same  place,  that  it  seems  probable  there  was  some  special 
undiscovered  source  of  error  in  his  work  which  would  make  it  undesi- 
rable to  include  his  results  in  the  table  of  comparisons  that  we  are  pre- 
senting. 


CARBONIC    ACID. 


67 


During  December  of  1888  and  April  of  1890,  a  few  scattered 
analyses  of  the  air  over  the  lawn  of  the  Johns  Hopkins  Hospital,  at 
Baltimore,  were  made  by  Abbott,  and  resulted  in  a  mean  of  3.750  parts 
of  carbonic  acid  per  10,000  parts  of  air. 

Of  the  nineteen  analyses  made  at  the  same  spot,  about  3  feet  above 
the  surface  of  the  soil,  under  varying  conditions  of  wind  and  weather, 
the  lowest  amount  found  was  3.300  parts  and  the  highest  was  5.700 
parts  in  10,000.  Upon  what  conditions  the  latter  figures  depend  it  is 
impossible  to  say.  It  was  supposed  that  the  wind  blowing  from  the 

TABLE  IV. 

Proportion  of  Carbonic  Acid  in  the  Air  of  Cambridge,  Mass.* 
Pettenkofer's  Method. 


Date. 

Time  of 
Day. 

Temp, 
of  Air. 
Cent. 

Barometer 
Inches. 

Locality. 

Vols.  of 
C02in 
10,000  Vols. 
Air. 

Remarks. 

1870. 

4  oo  P    M 

o     7g 

ing  previous  24  h. 
Fair     Wind   S  W 

"      30 

4.00  P.  M 
II  oo  A    M 

—  7° 
1    3° 

29.973 



3  08 

Cloudy.    "     S. 
Fair          "     S  W 

2    OO  P     M 

4-  6° 

,.64 

"     S 

1871. 
Jan.     2.. 

3- 
"        3-. 

3-  30  P.M. 
ii.oo  A.  M. 
2.30  P.  M. 

+  4° 

0° 

—  1° 

29.649     j 
30.063 
30.000 

College  Yard, 
20  Feet  N.  of 
Boylston  Hall. 

(,.„ 

l.io 
3-" 

Cloudy.    "     S.W. 
Clear.      " 

"           "     W 

4-- 

"          1 

3.  30  P.M. 
9  co  A.  M 

—  5° 

0° 

30.264 
30  i=;8 



3  32 

Cloudy     "     S  E 

Mean  of  n  Ob- 
servations... 

3-39 

*  These  analyses  were  made  by  H.  B.  Hill,  Assistant  in  Chemistry,  Harvard  University. 

boiler  vaults  toward  the  spot  at  which  the  analyses  were  in  progress, 
might  have  caused  the  excessive  amount  of  gas,  by  blowing  the  pro- 
ducts of  combustion  from  the  furnaces  to  this  point,  but  as  no  constant 
relations  between  winds  from  this  quarter  and  the  results  of  analyses 
could  be  established,  this  explanation  for  the  high  proportions  of  the 
gas,  had  in  part,  to  be  abandoned.  On  December  23d,  however,  at  a 
point  a  little  nearer  (about  50  yards)  to  the  furnaces,  a  distinct  odor  of 
sulphur  dioxide  was  noticed  in  the  air,  and  an  analysis  made  immedi- 
ately at  this  point,  resulted  in  5.100  parts  of  carbonic  acid  in  10,000 
air.  It  was  this  result  that  suggested  the  probable  explanation  for  some 


68 


CARBONIC    ACID. 


of  the  high  figures  ;  but  as  stated,  no  constant  connection  between 
winds  from  this  quarter  and  excessive  proportions  of  carbonic  acid  in 
the  air  could  be  established. 

As  a  portion  of  this  lawn  is  "made  ground,"  analyses  of  the  soil 
air  were  made  and  resulted  in  showing  a  proportion  of  carbonic  acid  at 
10  inches  below  the  surface  of  the  soil  of  53.1  parts  in  10,000  ot  air, 
and  at  5  feet  of  120.2  parts  in  10,000  of  air,  so  that  the  irregular 
diffusion  of  this  gas  from  the  soil  into  the  lower  strata  of  the  atmos- 
phere is  most  probably  the  reason  for  the  variations  found,  and  in  the 

TABLE  V. 
CO %  in  the  Air  of  Open  Fields,  Forests  and  Mountains. 


Observer. 

Place. 

CO2  in  io,oco. 

f 

Open  fields  near  Dieppe  
In  a  young  forest  

2.942 
2    QI7 

At  the  same  time  over  the  open  fields 
(exp.  station) 

2    QO2 

Over  a  blossoming  clover  field 

2    8q8 

Reiset             .   .           « 

At  the  same  time  over  the  open  fields 

(exp.  station)  

2    QI  => 

Over  a  barley  field     

2.829 

* 
| 

At  same  time  over  the  open  fields  (exp. 
station) 
In  a  field  near  a  sheep  herd  (300  head) 

Montsouris      .  .        

2.933 
3.I78 

^  020 

1876 

2    ^QO 

1877 

2    84.O 

T,               P     T 

1878 

<J     /ICO 

1870 

^    2QO 

1880                        

2    7OO 

Armstrong 

Grasmere  (Westmoreland)     

2.960 

Miintz  &  Aubin 

Open  field 

2    880 

Uffelmann 

Air  of  country  near  Rostock 

2    79-3   66 

Ebermeyer 

Bavarian  Highlands 

3  20 

light  of  Fodor's  experiments  made  at  Budapest,  I  am  inclined  to 
accept  this  latter  suggestion  as  the  explanation  of  the  inconstancies  in 
the  results.  Fodor  found  that  the  variations  in  the  amount  of  carbonic 
acid  in  the  air  for  about  6  feet  above  the  surface  of  the  soil  were  plainly 
due  to  diffusion  of  this  gas  from  the  soil. 

Saussure,1  in  1830,  clearly  demonstrated  that  the  presence  of  large 
bodies  of  water  has  a  very  appreciable  influence  upon  the  proportion 
of  carbonic  acid  in  the  atmosphere  above  them. 
1  Saussure.     Ann.  Chim.  and  Phys.,  XLIV.,  1830. 


CARBONIC    ACID. 


69 


From  simultaneous  analyses  made  of  the  air  from  the  center  of 
Lake  Geneva  and  over  the  land  near  the  bank,  he  found  the  average 
proportion  of  carbonic  acid  to  be  a  little  less  in  the  air  from  over  the 
lake  than  in  that  from  over  the  land  near  the  lake. 

Vogel1  had  likewise  obtained  similar  results,  demonstrating  the 
abstraction  of  this  gas  from  the  air  by  bodies  of  water. 

Kriiger2  failed  to  detect  its  presence  in  the  air  over  the  Baltic. 

TABLE  VI. 

Comparison  Between  the  Amount  of  Free  Carbonic  Acid  Fjund  in  the  Air 
of  Cities  and  That  of  the  Country. 


Analyst. 

Place  at  which  Analyses  were  made. 

CO,  in  10,000 

Difference. 

<3.e  Saussure    1830, 

$  Chambery,  near  Geneva  

4  37    ) 

32  analyses 

(  Geneva  

4.68    C 

0.31 

{  St.  Cloud.                        

4.13     ) 

Boussingault  

1  Paris 

'    J     J. 

414.     i 

O.OI 

Boussingault        & 
Levy    Sept    and 

j  Andilly  (near  Montmorency)  .  .  . 

2.Q8     ) 

Oct  ,  1844,  2  ex- 

I  Paris  .           .  .           

^        I 
3-17     \ 

0.19 

experiments  .... 
Smith  

(  Manchester  (fields  about)  

3.69     I 

0.73 

\  Manchester  (in  city)  
j  Madrid  (outside  the  city) 

4.42     $ 
4.  5O     ) 

Luna  

^•o^    f 

0.70 

j  London  (in  open  parks)  . 

5.20    ) 

o  oi      ) 

Smith  

J             f 

0.40 

Uffelmann  

(  Rostock  (in  city)  3^10  to  4.04,  mean 
•\Rostock  (in  country)  2.79  to  3.66, 

3-41    ) 

3.57^ 

0.34 

(  mean 

3  23     j 

The  conclusions  which  were  drawn  from  these  experiments,  were 
to  the  effect  that  the  air  over  the  open  sea  would  be  found  to  be  free 
from  CO2. 

Emmet  and  Dalton,3  in  1836,  showed  conclusively  that  carbonic 
acid  is  present  in  the  air  of  mid-ocean. 

Levy,4  at  the  request  of  the  French  Academy,  in  1848,  made 
a  series  of  analyses  of  the  air  over  the  sea.  His  work,  which 

i Vogel.     Ann.  Phil.  N.  S.,  VI.,  75. 

8Kruger.     Schw.  Jour.,  XXXV.,  379. 

3Emmet  and  Dalton.     Phil.  Mag.,  XL,  225. 

4Annales  de  Chim.  et.  d.  Phys.     Serie  3,  Tome  XXXIV.,  5. 


7o 


CARBONIC    ACID. 


was  done  while  on  a  voyage  from  Havre  to  Santa  Marta,  resulted  as 

follows: 

TABLE  VII. 


Date. 

Condition  of    Weather. 

Lati- 
tude,    N. 

Long.  W. 
of    Paris. 

CO2  in 

10,000, 
Each   the 
Mean  of  3 
Analyses, 

Dec    i    1847 

Cloudy           .            

0          ' 

47—  ^O 

0           ' 

JQ_C 

4  881 

Cloudless     .                

47—  oo 

I  *}—  O 

1  ^88 

8 

Few  Clouds  ..       .       

•2C—4O 

2O-T? 

c  407 

17 

Cloudless     

22—  ^ 

•IQ—  O 

c.77i 

18 

21—  4^ 

4.1—  a 

^  346 

18 

Few  Clouds  

21—  Q 

42-2^ 

5  42° 

IQ 

Cloudless 

2o—^5! 

A  a—  T  c 

1  188 

26 

1C—  AQ 

64—28 

5  288 

28  

(i 

14-6 

70-4 

5  °93 

OQ 

it 

12—  G. 

76-O 

c  143 

•5T 

4, 

3  7^7 

Mean  .  .  . 

..4.630 

In  addition  to  the  above  Levy  found  the  day  air  to  be  much  richer 
in  CO 2  than  air  taken  at  the  same  place  at  night.  For  example,  he 

found: 

Mean  of  7  day  experiments,   5.299  CO8  in  10,000. 
Mean  of  4  night  experiments,  3.459 

1.840 

The  means  of  analyses  made  by  Levy  at  about  midway  between 
the  continents  at  the  center  of  the  ocean,  and  at  the  same  hours  in  the 
night  and  day,  were  as  follows: 

Carbonic  acid  at  3  A.  M.  =  3.346 
"  3  P.  M.  =  5.420 

2074 

He  attributes  this  phenomenon  to  the  dissolution  and  admixture 
with  the  atmosphere,  of  the  gas  from  the  surface  of  the  sea  in  con- 
sequence of  the  warming  of  the  water  by  the  sun's  rays. 

From  Levy's  experiments  it  would  seem  that  the  sea  air  is  richer 
in  CO2  than  that  over  the  continents,  and  that  the  increase  in  the  pro- 
portion of  this  gas  was  due  to  the  warming  action  of  the  sun  upon  the 
superficial  layers  of  the  ocean,  from  which  the  acid  is  disengaged. 

This  conclusion  is  contrary  to  that  arrived  at  by  Kruger,1  who 
believed  the  sea  to  abstract  CO2  from  the  atmosphere. 

7.  J.,  XXXV.,  379),  and  Vogel  (Ann.  Phil.  N.  S.,  VI.,  75). 


CARBONIC    ACID. 


They  differ  very  materially  also  from  those  arrived  at  by  Thorpe 
and  by  Muntz  &  Aubin,  the  result  of  whose  work  appears  in  the 
following  tables. 

In  considering  the  results  given  by  Levy,  which  are  much  higher 
than  those  obtained  by  subsequent  observers,  the  criticism  of  Dr. 
Frankland  upon  the  methods  employed  by  Levy,  to  which  reference 
has  already  boen  made,  must  not  be  lost  sight  of. 

Thorpe,1  during  1865-66,  conducted  a  series  of  analyses  upon  the 
atmosphere  of  the  sea.  His  first  series  of  experiments,  the  details  of 

TABLE  VIII. 
.  COa  in  10,000  Vols.  Air  Over  Irish  Sea.     Pettenkofer^s  Method. 


TEMP.  OF 

CARBONIC. 

AIR. 

ACID. 

Temp. 

Date. 

Bar. 

of 
Sea. 

Wind,  Etc. 

Dry. 

Wet. 

ist 
Exp 

Exp. 

1865. 
Aug.  4... 

762.5 

16.4 

ii  .  i 

16.0 

N.W.xW.,  very  light. 

2.66 

3-°7 

Dav  very  fine  and 

clear. 

"       5--- 

762  ;O 

13-9 

12.  Q 

15.0 

S.W.xS.  light  breeze. 

2.92 

3-05 

''       5  •• 

761  .2 

16.1 

14.4 

15.0 

S.W.xS. 

3-08 

3-21 

"       7--- 

753-4 

14.2 

13-3 

15.0 

S.W.xS.,  light. 

3-3° 

3.22 

Baryta-water  ex- 

11      7..- 

757-5 

17.2 

15-1 

15-6 

N.W., 

3-20 

3-15 

posed  3  hours 
Sunny  —  very  fine. 

"      8... 

760.2 

13-6 

12.2 

15.0 

N.  N.W.,  moderate. 

3.06 

3-19 

"      8  .. 

761.0 

18.3 

I3-I 

16.0 

N.  N.W.,  light  breeze. 

3-32 

3.02 

Fine  and  sunny. 

"       9-- 

758.7 

«1.J 

12.2  . 

15-0 

S.W.xW.,      " 

2-93 

3.10 

"      9... 

756.4 





15-0 

S.xW.,  moderate. 

3  09 

3-23 

Rain. 

"       10... 

249-3 

15.0 

11.9 

14-5 

S.xW.,  fresh. 

3-n 

3-" 

Very  wet,  rain  all 

day. 

"       12... 

750-5 

*3  4 

II.9 

M-5 

S.W.xW.,  strong. 

3-09 

3.10 

Windy.     Rain  for 

nthto  i6th. 

"     16.. 

752.3 

14.7 

12.8 

15.0 

N.W.xW.,  light. 

2.93 

2.95 

"     17-.. 

753-i 

13-9 

12.8 

15.0 

W.  S.W.,  fresh. 

3   " 

2.94 

Baryta-water  ex- 
posed 6  hours. 

Hours  of  observation,  4  A.  M  ,  4  p.  M.    Thorpe's  Table. 

which  will  be  found  in  Table  VIII.,  were  made  upon  the  air  over  the 
Irish  Sea,  at  a  point  nearly  equally  distant  from  the  coasts  of  England, 
Ireland  and  Scotland.  As  a  mean  of  twenty-six  analyses,  he  found 
that  carbonic  acid  was  present  in  the  air  in  the  proportion  of  3.082 
vols.  in  10,000  vols.  of  air. 

His  experiments  upon  the  air  of  the  Atlantic  gave,  as  a  mean  result 
of  fifty-one  experiments,  the  proportion  of  2.953  vols.  CO2  in  10,000 
vols.  of  air. 

Thorpe— Mem.  Lit.  Phil.  Soc.  (3)  Vol.  IV. 
Thorpe — Jour.  Chem.  Soc.  London,  1867,  Vol.  XX.,  p.  189. 


CARBONIC    ACID. 


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CARBONIC    ACID. 


73 


The  general  mean  of  the  seventy-seven  experiments  being  3  parts 
CO2  in  10,000  parts  air,  a  proportion  less  by  1.63  parts  in  10,000,  than 
was  found  by  Levy. 

The  differences  in  the  results  obtained  by  these  two  observers,  can 
only  be  reconciled  by  a  comparison  of  the  methods  employed.  The 
method  of  von  Pettenkofer,  which  was  employed  by  Thorpe,  possesses 
a  much  greater  claim  to  accuracy  than  the  eudiometric  method  of 
Regnault  and  Reiset,  employed  by  Levy. 

TABLE  X. 

Proportion  of  CO2  in  the  Air  of  Tropical  Brazil  During  Rainy  Season. 

(Thorpe}. 


Date. 

Hour. 

Bar. 
m.m 

Temp,  of 
Air. 

Wind,  Etc. 

C02in 

10,000  Vols. 
of  Air. 

Dry. 

Wet. 

ist 
Exp. 

2d. 
Exp. 

1866. 
April    3. 

41         4 

4  20  P.  M. 
3.  oo  P.  M. 

762.0 
761.4 

23-4 
29.0 

™} 

Light  air. 
.  Overcast. 
Little  wind. 
Gloomv. 

3-i9 
3-44 

3   I4 
3-35 

After  6  hours  heavy  and 
incessant  rain. 
Just  previous  to  a  storm. 

11       16. 
"       16. 

11.20  A.  M. 
3.  45  P.  M. 

766.0 
763-5 

30.1 
25  6 

26.2  j- 

N.E.     Light 
breeze. 
N.E.    Gentle 
breeze. 

3-47 

3-22 

•;.;, 

Cloudy.      Much  rain  on 
previous  night. 
After    ij^    hours     heavy 

18. 

9.25  A.M. 

766.0 

27.2 

»5..j 

N.E.     Little 
wind. 

3-27 

3-12 

rain. 
Cloudy.    DuH. 

41       18. 

3.05  P.  M. 

g 

25  9 

2" 

322 

After  rain. 

2.  30  P.  M. 

762.5 

28.9 

25'6> 

M.E.xE.Fine 
breeze. 

3-3° 

3.12 

Sunny. 

"           21. 

12.50  P.  M. 

764  o 

33  3 

26.6  f 

N.E.    Gentle 
breeze. 

3  4i 

3.28 

Fine. 

44           23. 

I    20  P.  M 

764.5 

*., 

| 

25-9J- 

N.E.  Gentle 
breeze. 

3.12 

3-27 

Fine  and  sunny. 

14           24. 

2  35  P.  M 

764.0 

32.3 

25-  6  f 

M.E.    Gentle 
breeze. 

3-i6 

3.48 

Clear. 

May      4. 

2.50  P    M. 

763.1 

29.6 

26.6} 

M.  N.E.  Fine 
breeze. 

3-32 



Fine. 

41          7- 

12. 

44        18. 

3.  30  P.M. 
I.  40  P.  M 
12.  IS  P    M 

762.0 
761.5 

767      ^ 

26.9 
27.4 

•3O   8 

24.6  >• 
25-6  f 

Variable 
and  light. 
N.  N.E.  Fine 
breeze. 
N.E.  Gentle 

3-07 
3-24 
3-  32 

3  H 
3-35 
3.28 

Gloomy. 

Gloomy.        Just     before 
wind  and  rain  storm. 

'             21 

M.  A  .   A  ^     X    .     1T1  . 

12   45  P.  M 

1^*3  *  J 

762.5 

JW.U 

2Q.8 

25.6 

breeze. 
M.E. 

3-31 

3-29 

Fine  and  sunny. 

23. 

11.45  A.  M. 

764-5 

32    2 

27-2 

Fine  breeze. 

3  45 

3-32 

Cloudy. 

26. 

i.  oo  P.  M. 

764-5 

3^-7 

25-0  f 

Fresh 
breeze. 

3-49 

3-3° 

Little  rain  for  past  3  days. 
Fine. 

The  details  of  Thorpe's  experiments  on  the  Atlantic  will  be  found 
in  Table  IX. 

From  his  experiments  Thorpe  concludes: 

(i.)  That  the  sea  does  not  act  in  increasing  the  amount  of  atmos- 
pheric carbonic  acid. 

(2.)  But  that,  on  the  contrary,  the  air  over  the  sea  contains  a 
much  smaller  proportion  of  carbonic  acid  than  the  air  of  the  land, 


74  CARBONIC    ACID. 

although  the  influence  of  the  sea  in  abstracting  the  gas  from  the 
atmosphere  is  not  so  great  as  the  older  experiments  of  Vogel1  and 
Kriiger2  would  indicate. 

(3.)  That  the  mean  quantity  of  carbonic  acid  contained  in  the 
normal  atmosphere  over  the  ocean  is  3.00  vols.  in  10,000  vols.  of  air. 

(4.)  That  the  proportion  is  constant,  or  nearly  so,  in  different 
latitudes. 

(5.)  That  the  proportion  is  not  sensibly  influenced  by  the  different 
seasons  of  the  year. 

(6.)  That  the  proportion  does  not  experience  any  perceptible 
diurnal  variations. 

Miintz  &  Aubin3  give  the  following  : 

TABLE  XI. 

Carbonic  Acid  Analyses  Made  on  Board  the  Ship  " Romanche  "  in  1883  ; 
Open  Air,  Over  the  Sea. 

•  Sept.  so,  South  Atlantic,     {  1™^°J^'  (- *-74  CO,  in  IO,ooo 

N*-*8-    "  IfeV-o^f 2-"co°"    " 

Ife^^f ^7.00."       " 

&*%&£?}*•          ..*.7°CO.  " 

Oct.  16.  North  Atlantic,      $£*ffi£$*-  \ 2.49  CO2    "        " 

0*31,         "  "  |  &Xo'n°or^t;  !' ^CO*    "       "' 

Mean,  2.68  CO2   " 

This  mean  for  the  observations  upon  the  high  seas  is  almost  identical  with 
the  mean  of  their  observations  in  the  Northern  and  Southern  Hemispheres  : 

Northern  Hemisphere  =  2.84  CO2  in  10,000  vols.  air. 
Southern  Hemisphere  =  2.56  CO2    "       "         "        " 

Mean  ==  2.70  CO 2    " 
High  seas,  mean  =  2.68  CO2    " 


Thorpe's4  experiments  upon  the  air  of  tropical  Brazil  gave  him  as 
a  result  of  31  analyses  a  mean  of  3.28  CO3  in  10,000. 

1  Vogel— Ann.  Phil.  N.  S.,  VI.,  75. 

2  Kruger— Schw.  T.  XXXV.,  379. 

3  Comptes  Rendus,  Tome,  98,  1884,  p.  487. 

4  Thorpe — Jour.  Chem.  Soc.,  London,  1867,  Vol.  XX.,  p.  199. 


CARBONIC   ACID.  75 

His  experiments  were  made  at  Para  during  the  months  of  April 
and  May,  1866. 

Para,  the  principal  port  of  entrance  to  the  Amazon,  is  located  on 
the  river  Gram-Para,  about  80  miles  from  the  sea,  lat.,  i°  27'  S.; 
long.,  48°  28'  W.,  and  is  directly  on  the  border  of  a  vast  forest,  reach- 
ing to  the  sea.  For  the  greater  portion  of  the  year  the  trade  winds  of 
the  Atlantic  blow  across  the  forest. 

The  detailed  results  of  his  experiments  made  at  this  place  will  be 
found  in  Table  X. 

The  direction  of  the  wind  at  certain  places  is  seen  to  have  a  slight 
effect  upon  the  amount  of  CO2  present  in  the  atmosphere.  Fr. 
Schulze1  has  demonstrated  that  in  Rostock  the  air  is  seen  to  contain 
less  of  this  gas  when  the  wind  is  from  the  sea  than  when  it  comes  from 
over  the  land.  Blochmann2  found  the  same  to  be  true  for  Konigsberg 
and  Uffelmann3  has  confirmed  Schulze's  observations  at  Rostock. 

The  means  of  all  of  Uffelmann's  observations  at  Rostock  are  as 
follows  : 

N.W.  wind  =  3.49  vols.  CO2  in  10,000  vols.  air. 

N.      "     ==3-38 

E.       "     =3-71 

S.E.       "     =  3.62 

S.W.       "     =3-50 

W.       •'     =3.58 

« 

The  experiments  are  too  few  in  number  to  permit  of  any  positive 
conclusions  being  drawn. 

After  heavy  rains,  and  particularly  when  they  have  continued  for 
any  considerable  length  of  time,  Uffelmann  observed  a  diminution 
in  the  average  proportion  of  CO2  present  in  the  air  of  the  same  place. 

He  found  in  the  yard  of  the  University  at  Rostock  the  following 
conditions  : 

j  April  26,  1887 Cloudy , =  3.66  COa  in  10,000  ) 

(      "      27,    "    After  very  heavy  rain.   ...  =  3.40          "  "      ) 

\  May    29,    "    Heavens  almost  clear =3.58  "      ) 

j     "       30,    "    After  heavy  rain =3.39  "  "      j 

July    15,    "    After  very  heavy  rain =  3.28  "  " 

It  seems  from  these  figures  that  a  portion  of  the  carbonic  acid  is 
washed  from  the  atmosphere  by  the  rain  in  its  passage  to  the  earth, 

1  Schulze,  Landwerthschaftl,  Versuchstation,  Bd.  LXXIV. 

2  Liebig's  Annalen,  Bd.  CCXXXVII. 

3  Arch.  f.  Hyg.,  1888,  p.  286. 


76  CARBONIC    ACID. 

This  view  is  strengthened  by  the  experiments  of  Reichardt1,  who  found 
2  c.c.  of  CO2  in  a  litre  of  rain  water. 

On  the  other  hand  the  proportion  of  carbonic  acid  in  the  air  is 
seen  to  be  very  much  greater  during  heavy  snow  falls  and  fog. 
Schulze2  and  Uffelmann3  observed  this,  the  latter  finding  for  the  same 
locality  : 

During  snow  storm,  December  18,  1886,  3.96  CO2  in  10,000. 
"          "          "  March  12,  1887/3.67 

"          "          "  "      22,     "     3.81        " 

During  Fog,  February  20,     "      3.74 

22.       "        3.70 

"         "  May  28,     "      3.96 

•'     29,     "     4.00 

Average  for  one  year,  daily  observations  at  this  place  gave,  under 
all  conditions,  3.51  CO2  in  10,000. 

The  results  of  analyses  of  the  air  at  different  altitudes,  have  led  to 
opposing  opinions.  De  Saussure,4  in  1831,  found  that  the  air  at  „ 
mountain  tops  was  richer  in  carbonic  acid  than  that  over  the  low  lands. 
He  attributes  these  differences  to  the  action  of  the  more  abundant 
vegetation  of  the  low  lands  in  decomposing  the  carbonic  acid  in  the 
atmosphere  immediately  above  them — whereas,  on  the  mountain  tops, 
the  vegetable  growth  is  scant,  and  indeed  frequently  absent,  so  that 
there  is  an  absence  of  this  continuous  draught  upon  the  CO2  and  in  con- 
sequence, its'  amount  is  not  diminished  by  this  cause.  He  believes, 
moreover,  that  the  relative  amount  of  moisture  in  the  high  and  low- 
lying  lands  likewise  plays  a  part  in  the  diminution  of  the  proportion  of 
this  atmospheric  constituent — the  moist  low  lands  having  the  power  to 
take  up  a  greater  proportion  of  the  gas  than  the  dry  lands  of  the 
mountain  tops. 

The  experiments  of  Tissandier,6  led  him  to  adopt  a  similar  view. 
His  results  were  obtained  from  samples  of  air  collected  during  a  balloon 
ascent.  Tissandier  found  that  the  air  at  an  altitude  of  2,920  feet  gave 
him  2.140  vols.  of  CO2  per  10,000,  and  that  at  an  altitude  of  3,281  feet, 
he  obtained  3.00  vols.  CO2  in  10,000.  The  results  of  the  latter  observer, 
are,  as  pointed  out  by  Fodor,6  open  to  question,  by  reason  of  the 
methods  employed  by  him.  He  allowed  the  air  which  was  to  be  analyzed 

1  Reichardt,  Arch.  f.  Pharmacie,  Bd.  CCVL,  p.  193. 

8  Ebenda. 

3  Ebenda. 

4De  Saussure,  Ann.  d.  Chim.  e.  d.  Phys.  XLIV.,  1831. 

5 Tissandier,  Comptes  Rendus,  1875,  Tome  17,  page  976. 

G  Fodor,  "  Luft,  Boden  und  Wasser,"  Braunschweig,  1881. 


CARBONIC    ACID.  77 

to  pass  over  potassium  hydroxide,  by  which  the  carbonic  acid  contained 
in  it  was  absorbed.  The  CO2  was  then  liberated  from  its  carbonate 
thus  formed  by  the  substituting  action  of  other  acids,  and  its  volume 
measured  eudiometrically,  a  method  known  to  admit  of  a  greater 
degree  of  errors  than  the  process  of  titration  now  in  vogue. 

In  opposition  to  these  views  stand  the  results  of  work  done  by 
Truchot,1  Muntz  &  Aubin,2  Angus  Smith,3  and  Fodor.4 

Truchot's  analyses,  made  at  different  altitudes,  resulted  as  fol- 
lows : 

COa  in  10,000. 

Clermont-Ferrand,  1,296  feet  above  sea-level,  mean  of  3  analyses,  3.13. 
Puy  de  Dome,          4,774  Aug.  27th,  2.03. 

Pic  de  Sancy,  6,181  "  "          Aug.  2gth,        -          1.72. 

Muntz  &  Aubin's  analyses  at  high  altitudes,  gave  for  Pic  du 
Midi,  9,439  feet  above  sea,  2.86  CO2  in  10,000. 

Angus  Smith's  work,  led  him  to  lay  down  the  following  probable 
means  for  different  altitudes  : 

High  altitudes,  less  than  1,000  feet  =  3.37  CO3  in  10,000. 

"          between  i, ooo  and  2,000  feet  =  3.34    "  " 

"         2,000    "    3,000     "    =3.32    "  " 

"          above  3,000  feet  =3-36    "  " 

Smith's  work,  can  hardly  be  accepted  as  showing  any  marked  dif- 
ferences between  the  air  at  the  altitudes  in  which  his  analyses  were 
made.  The  means  of  his  analyses,  made  at  mountain  tops  in  Scotland 
and  over  the  low  lands  at  the  foot  of  these  mountains,  were  : 

Mountains,  3,281  feet  high — average  =  3.32  CO2  in  10,000. 
At  foot  of  these  mountains —       "        =  3  41     "  " 

If  one  considers  for  an  instant,  the  ceaseless  motion  constantlyan 
progress  in  the  atmosphere  at  large,  motion  in  the  form  of  air  cur- 
rents, resulting  from  variations  in  temperature  and  from  the  natural 
diffusion  between  gases  of  different  constitution,  it  appears  somewhat 
irrational  to  formulate  a  law  that  an  atmospheric  stratum  of  one  altitude 
would  contain  a  constantly  larger  proportion  of  a  gas  than  that  at  a 
higher  or  a  lower  level.  It  is  reasonable  to  suppose,  that  at  any 
given  point  of  constant  altitude,  there  may  be  variations  from  time  to 
time  in  the  proportion  of  its  atmospheric  constituents,  but  that  it  will 

1Truchot,  "  Comptes  Rendus,"  Tome  77,  1875. 

2Muntz  &  Aubin,  Comptes  Rendus,  Tome  92,  pp.  247,  1299. 

3Smith,  "  Air  and  Rain,"  1872. 

4Fodor,  loc.  cit. 


CARBONIC    ACID. 


always  contain  a  larger  or  a  smaller  proportion  of  any  of  its  con- 
stituents (conspicuously  local  causes  being  excluded)  than  another 
place  a  few  hundred  feet  higher  or  lower,  and  equally  favorably  located, 
is  opposed  to  all  physical  laws  bearing  on  gases  when  allowed  to 
circulate  freely. 

For  the  atmosphere  immediately  above  the  earth's  surface,  how- 
ever, it  is  certain  that  at  different  levels,  different  proportions  of 
carbonic  acid  exist ;  those  layers  next  to  the  ground,  containing  con- 
stantly more  of  this  gas  than  the  layers  a  few  feet  above. 

Believing  the  ground  to  be  the  main  source  from  which  the  atmos- 
phere receives  its  CO2,  and  believing  it  to  be  the  great  cause  of  the 
fluctuations  in  the  proportion  of  this  gas,  which  are  known  to  occur  in 
the  air  of  different  places,  Fodor  was  strengthened  in  this  opinion  by 
the  result  of  comparative  analyses  which  he  made.  His  experiments 
were  for  the  years  1877-78-79,  at  Budapest. 

In  each  experiment  a  sample  of  air  was  taken  from  %  to  i  c.  m. 
above  the  ground,  and,  simultaneously,  a  second  sample  was  analyzed 
from  2J/2  m.  over  the  ground.  His  results  were  as  follows: 

TABLE  XII. 


18 

77- 

18 

r8, 

18 

79- 

i  c.  m. 
Above 
Ground. 

2%  m. 
Above 
Ground. 

i  c.  m. 
Above 
Ground. 

2^m. 
Above 
Ground. 

i  c.  m. 
Above 
Ground. 

2^m. 
Above 
Ground. 

January.. 

A    78 

3oq 

372 

q    q2 

37j 

February  . 

A     2C 

3q7 

q    64. 

2    7Q 

q    66 

March  

2    2Q 

4CQ 

q  60 

T    e;6 

2    48 

April.  . 

I    f>  ^ 

q      og 

q    8e 

3q  A 

May   . 

462 

4j  q 

522 

O4 

q  88 

June  

c    Sd 

4  68 

377 

34.O 

4  18 

3r  q 

July. 

A     12 

4  ii 

427 

q    C2 

3Q-7 

3c  7 

August  

4   74. 

4.    12 

6  69 

•*  87 

4cfi 

3  68 

September  

6   75 

4.   24. 

C     AC. 

4oc 

4.    ^2 

q    QO 

October.  . 

*  66 

416 

4      A  q 

41  e 

q    80 

q      76 

November.. 

C     Q2 

4.    14. 

3QI 

q      82 

December  

a    1C 

q    70 

q    84. 

.... 

The  table  shows,  that  for  the  greater  portion  of  the  year,  the  pro- 
portion of  CO2  in  the  air  immediately  above  the  ground,  is  greater 
than  that  found  2%  meters  higher  up. 

It  teaches  also,  that  during  many  months  in  the  year,  the  fluctua- 
tions in  the  amount  of  this  gas  present  in  the  air  immediately  above 
the  ground,  are  very  much  greater  than  that  in  the  higher  layers  of  the 
atmosphere. 


CARBONIC    ACID. 


79 


It  shows  particularly,  that  each  fluctuation,  either  an  increase  or 
diminution,  in  the  proportion  of  CO2  in  the  upper  layers  of  the  air,  is 
preceded  by  a  similar  fluctutation  in  the  air  immediately  over  the 
ground. 

From  this  it  follows,  that  the  proportion  of  carbonic  acid  in 
each  of  these  lower  layers  of  the  atmosphere,  stands  in  close  relation, 
the  one  to  the  other — the  lower  layer  acting  as  a  regulator  for  those 
above  it. 

From  the  foregoing  table,  the  conclusion  may  also  be  drawn,  that  the 
ground  may  possess  the  power  of  diminishing  the  CO2  in  the  higher 
layers  of  the  air,  for  in  several  instances  it  is  seen,  that  the  layer  of  air 
in  close  contact  with  the  ground  is  poorer  in  CO2  than  that  a  few  feet 
higher  up.  This  is  the  case  on  rainy  days,  and  especially  is  it  so  in 
spring  time. 

Fodor  shows  this  diminution  in  the  amount  of  CO2,  which  is  seen 
to  occur  in  the  lower  layers  of  the  air  on  rainy  days,  to  be  not  entirely 
due  to  the  absorption  of  this  gas  by  the  water,  but  rather  to  an  actual 
chemical  combination  which  occurs  between  it  and  the  moistened 
ground.  He  demonstrated,  experimentally,  that  if  ground  be  moistened 
by  water  containing  no  carbonic  acid,  that  it  will  actually  take  up  from 
fifteen  to  twenty  times  as  much  carbonic  acid  as  the  same  amount  of 

water  alone. 

TABLE  XIII. 

Comparison  Between  the  Amounts  of  Carbonic  Acid  Present  in  the  Air  of 

Florence  at  the  Surface  of  the  Ground  and  18  Meters 

Above  the  Surface.     (Roster.) 


.     Date. 

CO2  in  10,000  Parts  of  Air  at 

Difference. 

Ground  Level. 

18  m.  Above 
Ground. 

May  17—18 

3-37 
3-32 
3-47 
3-51 
3.31 
3.37 
3.29 
3.42 
3-12 

3.20 
3.05 
3-30 
3-  II 
3.07 
3.03 
3-04 
3-24 
2.79 

0.17 
0.27 
0.17 
0.40 
0.24 

0.34 
0.25 
0.18 
0.33 

IQ—  2O 

20-2  1        

21-22      

22-23  

2J.-2^ 

25-26                   

26-27  

27-23  

Mean  

3-35 

3.09 

0.26 

From  the  very  exhaustive  experiments  made  by  Feldt,  Heimann 
and  Frey  upon  the  air  of  Dorpat,  we  can  gather  but  little  to  explain 
the  fluctuations  constantly  in  progress  in  the  proportion  of  CO2  in  the  air. 


8o 


CARBONIC    ACID. 


Each  of  these  observers  found  monthly,  daily  and  hourly,  variations 
in  the  proportion  of  this  gas,  but  were  not  able  to  demonstrate  that 
these  changes  were  a  constant  accompaniment  of  any  condition. 

For  Spring,  Summer  and  Fall,  they  found  the  proportion  to  be 
almost  constant.  For  Winter,  it  was  a  trifle  higher.  In  referring  to 
this,  Frey  remarks  that  perhaps  this  difference  maybe  due  to  the  fewer 
experiments  that  were  made  in  Winter,  owing  to  inclemency  cf  the 

TABLE  XIV. 
Means  of  Day  and  Night  Observations  Upon  Atmospheric  Carbonic  Acid. 


Place. 

Day, 

Night. 

Observer. 

Florence,  at  level  of  ground.  . 
8  meters  above  ground.   . 

3.22 
3  46 

3-49 
3.76 

>  Roster. 

18     "            "            '*...... 

2    91 

3.27 

Orange  Bay,  Cape  Horn  
Dorpat     .       

2.563 
2.58 

2.556 
2.69 

Muntz  &  Aubin. 
Heimann. 

2.66 

2.67 

Feldt. 

Montsouris  

2.891 

3.084 

Reiset. 

Andrassan,  Scotland  

3.40 

3-88 

Muir. 

TABLE  XV. 
Daily  Fluctuation  of  CO2,  as  Observed  by  Frey  at  Dorpat. 


n 

Hour. 

Feb.,  March,  April, 
May, 

1887. 

June,  Jul}',  Aug., 
Sept., 
!888 

Oct.,  Nov.,  Dec., 
Jan., 

1889. 

in  for  the  i 
Months. 

umber  of 
periments, 

<D 

£  * 

K 

9-12  A.  M. 

2.49=mean  of  28  exp. 

2.56=mean  of    sjexp. 

2.  59=:  mean  of    95  exp. 

2-55 

180 

12-  3  P.  M. 

2.66                "      95     " 

2.53                     "           102       " 

2.53                      102 

^.56 

299 

3-6     " 

2  73                "       83     " 

2.45             "        90    " 

2.67                     ioi    ' 

2.62 

274 

6-  9     " 

2.69                u      66     " 

2.72             "       130    " 

2    C4                      "              69       " 

2.66 

265 

9-12     •' 

2.63                       "         12        " 

2.92             "        40    " 

2.61             "        88     " 

2.69 

140 

12-   3A.M. 

2.68     .           "      40     " 

3-°3              "         67     " 

2.8o       -             "             21       " 

2.88 

128 

3-  6     '' 

2.86              "         26     4' 

2.81              ''         19     " 

2.84 

45 

6-  9     " 

2.46               "      16     '* 

2.71               "         89     " 

2.6l                      "              6!       " 

2.64 

166 

weather,  and  partly  to  the  additional  consumption  of  oxidizable  carbon 
compounds  as  fuel  and  for  purposes  of  illumination. 

Heimann  believed  to  have  demonstrated  that  the  proportion  of 
carbonic  acid  in  the  air,  was  directly  proportional  to  the  barometric 
pressure,  and  inversely,  to  temperature  and  humidity. 

Frey,  who  repeated  the  experiments  with  this  point  in  view,  was 
unable  to  confirm  the  observations  of  Heimann. 


CARBONIC    ACID. 


8l 


TABLE  XVI. 
Doily  Fluctuation  of  Carbonic  Acid  in  the  Air  .Expressed  in  Parts  per  10,000. 


Date 

Place 

C( 

33 

Differ- 

Min. 

Max. 

ence. 

1869—71 

Rostock 

2    25 

7     A  A 

I    JQ 

Schulze 

Lund      .  .                 

2    37 

a    27 

O    9O 

Claeson 

Tabor  

3    O2 

4   O7 

I    O5 

Farsky 

1874. 

Dahne 

2    70 

41  7 

I    47 

Fittbopren 

1830  

Geneva  

3.  15 

7.37 

4.22 

Saussure. 

Madrid 

2    OO 

e    74 

•3    74 

Luna 

Manchester  ... 

2    85 

9   CO 

6  15 

Smith. 

1877-70.  . 

Budapest     

2.33 

417 

1.84 

Fodor. 

1877-85.  . 

Montsouris.  Paris     .... 

2.53 

3.60 

I.O7 

Levy. 

1875  

Paris  

2.91 

3  52 

0.61 

Reiset. 

Paris 

2  88 

4.22 

I    34 

Miintz  &  Aubin. 

1882.    ... 

Pic  du  Midi 

2.69 

3.OI 

0.32 

Miintz  &  Aubin. 

1886  

Florence.         

2.71 

4.19 

1.48 

Roster. 

TABLE  XVII. 

Difference   Between   the  Amount  of  Carbonic  Acid  Present  in   the  Air 
During  the  Day  and  Night.     (Roster.) 


Height  Above  the  Ground  at 
Which  Sample  Was  Taken. 

CO2  in  10,000  Yols.  of  Air. 

Difference. 

Day. 

Night. 

At  level  of  ground  
8  m.  above  ground 

3-22 
3.46 
2.91 

3-49 
3.76 
3-27 

0.27 
0.30 
0.36 

ki 

18  m.  "  " 

TABLE  XVIII. 

Monthly  Variations  in  the  Proportion  of  Free  Carbonic  Acid  in  the  Air  of 
Different  Places.     Expressed  as  Vols.  of  CO2  in  10,000  Vols.  of  Air. 


Months. 

Mont- 
souris, 
1871-85. 

Buda- 
pest, 
1877-79. 

Florence, 
1886. 

Rostock, 
1886-87. 

Dorpat, 
1888-89. 

Orange  Bay, 
Cape  Horn, 
1882-83. 

January  

3.04 

3.72 

2.92 

3.65 

2.69 

2.55 

February 

2   97 

3   65 

2.98 

3.68 

2.81 

2    71 

March   

2.96 

4.08 

2.99 

3.6i 

2.79 

2.55 

April 

2    98 

3  66 

2  95 

3   5O 

2    5O 

2    54 

May 

2    QQ 

3  84 

3.07 

3.51 

2.57 

2    65 

June.        

3.03 

3.87 

3.59 

3.42 

'    2.5O 

2.5O 

July.. 

2.99 

3-73 

3.28 

3.30 

2.6l 

2.75 

Auerust 

2  95 

3  89 

3.30 

3.28 

2.83 

September.  .  .           .    . 

2.97 

4.06 

3.20 

3-34 

2.67 

October 

2    9O 

4  02 

3  .OO 

3    54 

2.56 

2.  5O 

November 

2.87 

4  °3 

3.04 

3.63 

2.72 

2.60 

December  

2  94 

4.03 

2.99 

3-67 

2.5O 

2-53 

82 


CARBONIC    ACID. 


TABLE  XIX. 

Table  Showing  Seasonal  Variations  in  the  Proportion  of  Free  Atmospheric 
Carbonic  Acid.     Expressed  as  Vols.  of  COZ  in  10,000  Vols.  Air. 


Place. 

Winter. 

Spring. 

Summer. 

Autumn. 

Dahne1   

3.24 

3.37 

3-34 

3-39 

Budapest8.                   • 

3.8-3 

•2.84. 

1  8q 

4O4. 

Montsouris3                .  . 

3  OQ 

3.O7 

a  CK 

3  II 

Florence4  ... 

2.98 

3.OI 

q  47 

3.3Q 

Dorpat5  .  .           

2.72 

2.61 

2.66 

2.6l 

Rostock6   

3.67 

3-54 

3-34 

3.  5O 

Mean. 

^.26 

-?.26 

T  28 

•7    04 

Ammonia. — The  most  conspicuous  of  the  nitrogenous  products  of 
decomposition  that  are  found  in  the  air  is  ammonia.  It  is  everywhere 
present,  though  in  amounts  that  are  subject  to  the  widest  fluctuations. 
The  range  of  this  variation  can,  perhaps,  be  best  understood  by  refer- 
ence to  the  accompanying  tabulated  observations  made  at  different 
places  (taken  from  Roster's  book,  "  L'Aria  Atmosf erica.") 

TABLE  XX. 
Atmospheric  Ammonia. 


Date. 

Place. 

Mgs.ofNH, 
in  i  C.  M. 
of  Air. 

Analyst. 

May  

Miihlhausen,  4  rainy  days  

0.4250 

Graeger. 

Tune    July 

Irish  coast 

4  6400 

Kemp 

Aug.  and  Sept.,  1848.  . 
December 

Wiessbaden,  mean  for  40  days. 
Boston 

o.  1720 

I    ^^OO 

Fresenius. 
Horsford 

May  and  April 

Caen  (mean)                        

o  64.^0 

Pierre. 

Lyons,  mean  of  different  alti-  ) 
tudes,  7.5  m.—  23  m.     ....  f 

0.4450 

Bineau. 

Winter  and  Summer 

Calurie           

o  0910 

it 

July,  Aug.  and  Oct.  \ 

Clermont,  Fearand,  mean  of  ) 
7  observations                          \ 

1.5760 

Truchot. 

Puy  de  Dome  (1,446  m.)  
Pic  de  Sancy  (1,884  m.)  
Paris                                        .... 

2.1500 
5.3520 
o  0320 

Ville. 

1877-79  

Budapest.       .     .           

0.0413 

Fodor. 

1877-79  

Montsouris  .                 

0.0245 

Levy. 

1870 

Glasgow 

o  0310 

Official. 

1875-76    . 

Paris   mean  for  the  year 

o  0225 

Schloesing. 

1  Fittbogen  &  Haesselbarth,  loc.  cit. 

2  Fodor,  loc.  cit. 

3  Annuaire  d.  1'obs  d.  Montsouris,  1876,  '77,  '78, 

*  Roster,  loc.  cit. 

5Frey  Dissertation,  loc.  cit. 

•  Uffelman,  loc.  cit. 


79- 


CARBONIC    ACID.  83 

A  fair  average,  however,  of  the  amount  of  ammonia  normally 
present  in  the  atmosphere  may  be  obtained  from  the  following  table: 

TABLE  XXI. 

Paris  (analyses  in  the  city) 0.0320  mgs.  in  i  cubic  meter  of  air 

Budapest  (Fodor's  analyses) 0.0413     "       "       "  "          " 

Montsouris  (Levy's  analyses) .  0.0245     "       "        "  "          " 

Glasgow  (official  analyses) 0.0310    "       "       "  "          " 

Paris  (Schloesing's  analyses) ....  0.0225     "       "       "  •' 

Mean 0.0304    "       "       "  "          " 

Ammonia,  though  present  in  the  atmosphere  in  very  small  amounts, 
can  nevertheless  be  demonstrated  at  all  points  upon  the  earth's  surface. 

Its  relative  proportion,  is  seen  to  undergo  such  wide  fluctuations 
at  different  localities,  as  to  make  it  probable  that  it  is  largely  influenced 
by  local  conditions. 

It  exists  in  the  atmosphere  mainly  as  a  result  of  decomposition  of 
nitrogenous  substances,  though  a  certain  proportion  of  it  arises  as  a 
result  of  various  industries.  It  is  present  in  small  amounts  in  illumi- 
nating gas,  and  can  be  demonstrated  in  traces  in  the  exposed  air.  It 
is  usually  combined  with  carbonic  acid  in  the  air,  and  in  small  amounts 
with  nitrous  acid. 

With  elevation  of  temperature,  and  in  the  presence  of  sufficient 
moisture,  the  amount  of  this  compound  present  in  the  atmosphere  in 
the  neighborhood  of  decomposing  matters,  is  seen  to  increase.  From 
these  points,  it  is  in  part  disseminated  through  the  atmosphere,  to  be 
again,  in  part,  returned  to  the  earth  with  the  rain. 

Fodor  found  the  seasonal  variations  in  the  amount  of  atmospheric 
ammonia  of  the  air  of  Budapest,  as  depending  mainly  upon  variations 
in  temperature,  to  be  as  follows  : 

Winter,    0.0251  mgs.  NH3  in  i  cu.  meter  of  air  at  Budapest. 
Spring,     0.0303          "  "  "  " 

Summer,  0.0488 
Autumn,  0.0334          "  " 

Experiments  have  led  us  to  believe,  that 'ammonia  does  not  exist 
in  the  air  as  a  result  of  diffusion  from  the  deeper  layers  of  the  soil,  as 
was  at  one  time  supposed,  but  rather  as  a  result  of  the  manifold  pro- 
cesses of  decomposition  going  on  upon  the  surface  of  the  ground. 

The  experiments  of  Fodor  demonstrated  that  the  amount  of 
ammonia  present  in  the  atmosphere  is  dependent  entirely  upon  local 
causes :  it  is  most  affected  by  moisture  and  temperature.  It  is  seen  to 
diminish  with  almost  mathematical  regularity,  with  the  existence  of 
rainy  weather  and  fall  of  temperature,  and  to  again  increase  as  the 


84  CARBONIC    ACID. 

temperature  rises  after  a  rainy  spell.  Its  amount  was  changed  but 
little,  or  not  at  all,  by  winds  from  the  different  points  of  the  compass, 
and  particularly  was  this  the  case  with  winds  from  the  sea,  which, 
according  to  the  doctrine  of  Schloesing,  should  have  caused  an  increase, 
It  cannot  come  from  the  "  ground  air,"  properly  so  called,  as  the  follow- 
ing experiments  of  Fodor  show  : 

The  amount  of  ammonia  present  in  i  cubic  meter  of  air  from  the 
soil.  (Fodor). 

i  meter  deep.  4  meters  deep. 

March     to  May,  ground  air 0.0198  mgs.  0.0471  mgs. 

June         "  September,         "          0.0277  mgs.  0.0444  mgs. 

.    October  "  December,          "         0.0089  mgs.  0.0167  mgs. 

The  official  observations  made  at  Glasgow,  point  also  to  local  con- 
ditions as  potent  factors  in  influencing  the  amount  of  ammonia  in  the 
air. 

In  i  cubic  meter  of  air  from  different  localities,  the  following" 
results  were  obtained  : 

For  the  air  at  the  Western  Infirmary 0.015  mgs. 

"  "       Hospital,  Kennedy  Street 0.019  mgs. 

"  "       Sailors'.  Home ...    0.024  mgs. 

at  Colton 0.044  mgs. 

"  at  Sterling  Square 0.053  mgs. 

The  more  densely  populated  a  locality,  and  the  greater  the  extent 
of  manufacture  in  progress,  the  higher  is  the  proportion  of  atmospheric 
ammonia. 

Another  factor  that  is  potent  in  causing  irregularities  in  the 
relative  amount  of  ammonia  in  the  atmosn^ere,  is  rain.  With  every 
rainstorm,  a  certain  amount  of  this  substance  is  washed  from  the  air, 
as  can  be  demonstrated  not  only  by  a  diminution  in  the  amount  present 
in  the  free  atmosphere,  at  the  point  at  which  the  rain  fell,  but  also  by 
its  presence  in  the  collected  rain  water. 

Schloesing's  experiments,  made  at  Paris,  give  as  a  mean  amount 
of  ammonia  in  the  air  on  rainy  and  dry  days  for  one  year,  the  following 
figures : 

Rainy  days,  0.0175  mgs.  NH3  in  i  cubic  meter  of  air. 
Dry          "      0.0193  "  "  "  " 

From  Fodor's  standpoint,  the  hygienic  significence  of  free  ammonia 
in  the  atmosphere  are  its  indications  of  the  existence  of  nitrogenous 
decomposition  in  progress  at  neighboring  points  ;  it  may  be  taken  as  an 
index  of  the  intensity  of  this  decomposition,  and  may  serve  as  indicator 
of  the  presence  of  other  volatile  organic  products  thrown  off  along  with 
it  from  the  putrefying  substances. 


CHAPTER  V. 

CONDITIONS  WHICH  MAKE  VENTILATION  DESIRABLE  OR  NECESSARY — 
PHYSIOLOGY  OF  RESPIRATION — GASEOUS  AND  PARTICULATE  IMPU- 
RITIES OF  AIR SEWER  AIR — SOIL  AIR DANGEROUS  GASES  AND 

DUSTSIN  PARTICULAR — OCCUPATIONS,  OR  PROCESSES  OF  MANUFAC- 
TURE— DRYING  ROOMS. 

BEARING  in  mind  the  composition  and  the  more  important 
physical  properties  of  the  normal  or  free  atmosphere,  we  come 
now  to  the  consideration  of  the  changes  produced  in  it  by  animal  life, 
and  by  the  conditions  of  human  habitations  and  occupations,  which  make 
it  desirable  or  necessary  to  dilute  and  remove  the  air  which  has  thus 
been  rendered  more  or  less  unfit  for  respiration,  and  to  supply  fresh 
and  pure  air  in  its  stead  in  rooms  and  enclosed  spaces. 

In  the  open  air,  under  ordinary  circumstances,  as  has  been  shown 
in  a  previous  chapter,  the  difference  between  gases  of  different  densi- 
ties and  the  action  of  atmospheric  currents  produce  such  a  rapid  and 
thorough  mixture  and  dilution  of  gaseous  impurities  escaping  into  it, 
that  they  are  soon  made  innocuous  and  inoffensive.  Yet  this  is  not 
always  the  case,  and  in  enclosed  spaces  or  rooms  occupied  by  men, 
some  accumulation  of  such  impurities  almost  always  occurs,  requiring 
the  adoption  of  special  means  to  prevent  it  from  becoming  excessive. 

The  first  group  of  such  impurities  to  be  considered  is  that  due  to 
respiration,  and  to  exhalations  from  the  skin  and  alimentary  canal. 

Pure  air  contains  no  stored  force,  and  cannot  properly  be  called  a 
food.  Nevertheless,  its  oxygen  is  as  essential  to  nourishment,  growth, 
and  manifestations  of  muscular  force  as  are  the  substances  usually 
reckoned  as  alimentary  principles.  The  essential  feature  of  animal 
respiration  is  the  taking  in  of  oxygen  and  the  excretion  of  carbonic 
acid,  and  this  is  effected  chiefly  by  the  physical  process  of  diffusion 
between  the  air  and  the  gases  of  the  blood  through  the  thin  membranes 
forming  the  walls  of  the  air  cells  and  capillaries  of  the  lungs.  In  the 
human  lungs  there  are  between  five  and  six  millions  of  such  air  cells  or 
vesicles,  and  their  superficial  area  is  about  975  square  feet.  They  are 


86  PHYSIOLOGY    OF    RESPIRATION. 

connected  by  the  bronchial  tubes  with  the  wind-pipe,  which  communi- 
cates with  the  external  air  through  the  nose  and  mouth. 

The  lungs  are  contained  in  the  chest  cavity,  which  they  exactly 
fill  so  long  as  no  opening  is  made  in  the  chest  wall,  accommodating 
themselves  to  variations  in  its  size  and  shape.  When  the  chest  cavity 
is  made  larger  by  descent  of  the  diaphragm  or  by  ascent  of  the  ribs, 
the  action  is  similar  to  that  of  expanding  of  a  bellows,  and  the  air 
rushes  in  through  the  nose,  mouth  and  air  passages,  distending  the 
expansible  lung  and  equalizing  the  atmospheric  pressure  on  the 
interior  and  exterior  walls  of  the  chest.  This  act  of  inspiration  is  a 
muscular  movement.  The  lungs  contain  a  large  amount  of  elastic 
tissue  which  is  in  a  state  of  constant  tension,  and  when  the  muscular 
effort  required  to  expand  the  chest  relaxes,  the  lungs  contract,  expelling 
a  portion  of  the  air  which  they  contain.  Ordinary  expiration  is  thus 
for  the  most  part  due,  not  to  muscular  compression,  but  to  the  contrac- 
tility of  the  lung  tissue. 

The  lungs  never  give  out  all  the  air  they  contain  ;  after  the  most 
complete  expiration  possible  there.will  still  remain  in  them  from  100  to 
130  cubic  inches  of  air,  which  is  called  residual  air. 

After  a  normal  quiet  respiration,  an  additional  quantity  of  air  can 
still  be  expired  from  the  chest  equal  to  about  100  cubic  inches,  which 
is  called  reserve  or  supplemental  air.  The  volume  of  air  which  is 
taken  at  each  inspiration  and  expiration  is  called  tidal  air,  and  is  equal  to 
about  30  cubic  inches,  so  that  from  one-seventh  to  one-tenth  of  the  air 
in  the  lungs  is  renewed  at  each  respiration.  In  the  adult  the  number  of 
respirations  varies  from  16  to  24  in  the  minute — the  frequency  being 
affected  by  the  position  of  the  body,  the  age,  the  state  of  activity  of 
the  person,  the  density  of  the  surrounding  medium,  and  the  temperature 
of  the  blood.  Evidently  a  large  part  of  the  mechanism  for  the 
interchange  of  gases  in  the  lungs  must  be  by  the  process  of  diffusion 
from  the  larger  air  passages. 

The  changes  produced  in  air  by  respiration  are:  elevation  in 
temperature,  increase  of  moisture,  increase  in  volume,  and  changes  in 
its  chemical  composition. 

At  the  average  temperature  of  70°  F.,  the  temperature  of  the  air  as  it 
leaves  the  lungs  should  be  about  97°  F.,  which  implies  an  equivalent  loss 
of  heat  from  the  body.  When  the  external  temperature  is  very  low,  that 
of  the  expired  air  sinks  a  little;  thus  at  42°  F.  it  becomes  88°  F.  If 
the  external  temperature  is  above  100°  F.,  the  expired  air  may  be  cooler 
than  that  which  is  inhaled — the  temperature  depending  on  the  relative 
temperature  of  the  blood  and  the  surrounding  atmosphere. 


PHYSIOLOGY    OF    RESPIRATION.  87 

The  average  loss  of  heat  from  the  body  in  24  hours  due  to  respir- 
ation alone,  is  calculated  at  3.5  calories,  which  must  necessarily  again 
appear  as  such  in  the  surrounding  air,  and  consequently  elevate  its 
temperature. 

Although  inspired  air  almost  always  contains  more  or  less  vapor  of 
water,  it  is  rarely  saturated  when  it  enters  the  body;  however,  itcarries 
off  as  much  aqueous  vapor  as  it  is  possible  for  it  to  hold  at  the  tem- 
perature at  which  it  is  expired — thus  it  may  be  considered  to  be  satur- 
ated at  the  temperature  of  97°  F.  The  amount  of  water  removed  from 
the  body  by  respiration  of  course  varies  with  the  temperature  and  con- 
dition of  humidity  of  the  inspired  air,  but  as  an  average  for  24  hours 
the  amount  may  be  taken  as  255  grams  (9  ounces).  For  the  evapora- 
tion of  this  amount  of  water  from  the  lungs,  an  additional  amount  of 


CORRECTIONS: 

Page  87,  line    2,  instead  of    "3.5  calories,"  read    "  85,000  small  calories." 

"      "    14,        "         "     "  7.2  calories,"     "     "  192,000  small  calories." 

15.        1 0.7  calories,"     "     4<  275,000  small  calories." 


amount  of  change  occurring  in  the  air  of  the  room. 

The  chemical  alterations  in  air  due  to  respiration  are  diminution 
of  the  amount  of  oxygen,  and  increase  in  the  proportion  of  carbonic 
acid,  together  with  the  addition  of  certain*  volatile  organic  compounds, 
of  whose  nature  we  as  yet  know  but  little.  Expired  air  contains  about  5 
percent,  less  oxygen,  and  a  little  more  than  4  percent,  more  of  carbonic 
acid  than  that  which  is  inhaled. 

Comparing  the  chemical  composition  of  100  parts  of  the  free  at- 
mosphere with  100  parts  of  expired  air,  their  compositions  would  be  as 
follows  : 

i  Oxygen 20. 8 

Free  atmosphere K  Nitrogen 79 . 2 

( Carbonic  Acid o .  o  3-4  Vol. 

(Oxygen 15.4 

Expired  air. •<  Nitrogen 79.2 

(  Carbonic  acid 4.33-4  Vol. 


86  PHYSIOLOGY    OF    RESPIRATION. 

connected  by  the  bronchial  tubes  with  the  wind-pipe,  which  communi- 
cates with  the  external  air  through  the  nose  and  mouth. 

The  lungs  are  contained  in  the  chest  cavity,  which  they  exactly 
fill  so  long  as  no  opening  is  made  in  the  chest  wall,  accommodating 
themselves  to  variations  in  its  size  and  shape.  When  the  chest  cavity 
is  made  larger  by  descent  of  the  diaphragm  or  by  ascent  of  the  ribs, 
the  action  is  similar  to  that  of  expanding  of  a  bellows,  and  the  air 
rushes  in  through  the  nose,  mouth  and  air  passages,  distending  the 
expansible  lung  and  equalizing  the  atmospheric  pressure  on  the 
interior  and  exterior  walls  of  the  chest.  This  act  of  inspiration  is  a 
muscular  movement.  The  lungs  contain  a  large  amount  of  elastic 
t"""  '  '  — ~  n  rfntp  oLconstant  tension,  and  when  the  muscular 


respirations  varies  from  16  to  24  in  the  minute — the  frequency 
affected  by  the  position  of  the  body,  the  age,  the  state  of  activity  of 
the  person,  the  density  of  the  surrounding  medium,  and  the  temperature 
of  the  blood.  Evidently  a  large  part  of  the  mechanism  for  the 
interchange  of  gases  in  the  lungs  must  be  by  the  process  of  diffusion 
from  the  larger  air  passages. 

The  changes  produced  in  air  by  respiration  are:  elevation  in 
temperature,  increase  of  moisture,  increase  in  volume,  and  changes  in 
its  chemical  composition. 

At  the  average  temperature  of  70°  F.,  the  temperature  of  the  air  as  it 
leaves  the  lungs  should  be  about  97°  F.,  which  implies  an  equivalent  loss 
of  heat  from  the  body.  When  the  external  temperature  is  very  low,  that 
of  the  expired  air  sinks  a  little;  thus  at  42°  F.  it  becomes  88°  F.  If 
the  external  temperature  is  above  IOOQ  F.,  the  expired  air  may  be  cooler 
than  that  which  is  inhaled — the  temperature  depending  on  the  relative 
temperature  of  the  blood  and  the  surrounding  atmosphere. 


PHYSIOLOGY    OF    RESPIRATION.  87 

The  average  loss  of  heat  from  the  body  in  24  hours  due  to  respir- 
ation alone,  is  calculated  at  3.5  calories,  which  must  necessarily  again 
appear  as  such  in  the  surrounding  air,  and  consequently  elevate  its- 
temperature. 

Although  inspired  air  almost  always  contains  more  or  less  vapor  of 
water,  it  is  rarely  saturated  when  it  enters  the  body;  however,  it  carries 
off  as  much  aqueous  vapor  as  it  is  possible  for  it  to  hold  at  the  tem- 
perature at  which  it  is  expired — thus  it  may  be  considered  to  be  satur- 
ated at  the  temperature  of  97°  F.  The  amount  of  water  removed  from 
the  body  by  respiration  of  course  varies  with  the  temperature  and  con- 
dition of  humidity  of  the  inspired  air,  but  as  an  average  for  24  hours 
the  amount  may  be  taken  as  255  grams  (9  ounces).  For  the  evapora- 
tion of  this  amount  of  water  from  the  lungs,  an  additional  amount  of 
7.2  calories  of  heat  disappears — thus  makingthe  total  loss  of  heat  from 
the  body  in  the  process  of  respiration  10.7  calories.  A  large  part  of 
this  heat  made  latent  in  evaporation  reappears  as  such  in  the  surround- 
ing atmosphere  when  the  heat  is  given  up  by  the  condensation  of  the 
moisture.  The  greater  part  of  the  heat  and  moisture  imparted  to 
air  by  respiration  comes  from  the  upper  air  passages — very  little  com- 
ing from  the  air  cells. 

Since  air  leaving  the  lungs  saturated  with  moisture  at  97°  F.  must 
lose  a  portion  of  this  moisture  from  condensation,  as  its  temperature, 
falls  to  that  of  the  average  temperature  of  inhabited  rooms — namely,  65 
to  70°  F.,  we  see  that  the  air  of  a  room  containing  living  men  and 
other  animals  will  be  increased  in  temperature — the  amount  of  the  in- 
crease depending  on  the  amount  of  respiration  going  on,  and  the 
amount  of  change  occurring  in  the  air  of  the  room. 

The  chemical  alterations  in  air  due  to  respiration  are  diminution 
of  the  amount  of  oxygen,  and  increase  in  the  proportion  of  carbonic 
acid,  together  with  the  addition  of  certairf  volatile  organic  compounds, 
of  whose  nature  we  as  yet  know  but  little.  Expired  air  contains  about  5 
percent,  less  oxygen,  and  a  little  more  than  4  percent,  more  of  carbonic 
acid  than  that  which  is  inhaled. 

Comparing  the  chemical  composition  of  100  parts  of  the  free  at- 
mosphere with  100  parts  of  expired  air,  their  compositions  would  be  as 
follows  : 

(  Oxygen 20 . 8 

Free  atmosphere •<  Nitrogen 79. 2 

( Carbonic  Acid o.o  3-4  Vol. 

Oxygen 15.4 

Expired  air -\  Nitrogen 79-2 

Carbonic  acid 4.33-4  Vol. 


88 


CHEMISTRY    OF    RESPIRATION. 


Taking  the  daily  respiration  by  volume  as  10,800  litres  (346  cubic 
feet)  of  air  with  a  loss  of  5  per  cent,  of  oxygen  and  a  gain  of  4.37  per 
cent,  of  carbonic  acid,  it  is  seen  that  the  amount  of  oxygen  taken  up 
through  the  lungs  in  24  hours  is  583.2  litres  (20.4  cubic  feet)  by 
volume  or  833.9  grams  (12.818  grains)  by  weight. 

The  amount  of  carbonic  acid  excreted  from  the  lungs  in  the  same 
time  is  464.4  litres  (16.25  cubic  feet)  by  volume,  or  910  grams  (14.105 
grains). 

As  we  proceed  in  these  studies,  it  will  be  seen  that  one  of  the  most 
universally  employed  indices  for  the  determination  of  the  extent  to 
which  pollution  of  air,  due  to  human  exhalation  and  transpiration,  is  going 
on,  in  enclosed  spaces,  is  the  excess  of  carbonic  acid  over  and  above 
the  amount  usually  found  in  the  air.  Not  that  the  gas  has  any 
hygienic  significance  within  the  limits  ordinarily  observed,  but  experi- 
ence has  shown  a  constant  parallel  between  the  rate  of  its  production 
and  the  amount  of  organic  impurities  thrown  off  by  animals  and  human 
beings. 

The  ratio  between  the  amount  of  oxygen  absorbed  and  the  amount 
of  carbonic  acid  exhaled  varies  in  different  animals.  This  ratio,  called 

CO2 

by  Pfluger  the  respiratory  quotient,   being  ___  is  from  0.9  to  i.    in 

herbivora,  while  in  carnivora  it  is  from  0.75  to  0.8.     In  man  it  is  0.87. 
The  following  table  shows  for  different  animals  the  amount   of 
oxygen  used    per    kilogramme    of   body  weight  per   hour.     *     *     * 
(I.  Munk,  Physiologic  des  Menschen,  etc.,  1888.  p.  82). 


Animal. 

o  in  Grams. 

Respiratory 
Quotient." 
CO2 
(  > 

Cat                 

I   OO7 

O   77 

Dog      

i  .183 

o  75 

Rabbit 

o  918 

O    Q2 

Hen          .                     

I    3OO 

O   93 

Small  singing  birds 

II   360 

o  78 

Frog  .... 

o  084 

o  6^ 

Cockchafer.  

1  .019 

o  81 

Man   . 

O   4.17 

o  78 

Horse. 

o  563 

O   Q7 

Ox  

o.  552 

o  98 

Sheep  .  . 

0.490 

o  98 

Smaller  animals,  therefore,  have,  as  a  rule,  greater  intensity  of 
respiration  than  larger  ones.  In  small  singing  birds  the  ;ntensity  is 
very  remarkable,  and  it  will  be  seen  that  they  require  ten  times  as 


CHEMISTRY    OF    RESPIRATION.  89 

much  oxygen  as  a  hen.  On  the  other  hand,  the  intensity  is  low  in  cold- 
blooded animals,  Thus  a  frog  requires  135  times  less  oxygen  than  a 
small  singing  bird.  The  need  of  oxygen  is  therefore  very  different  in 
different  animals.  A  guinea-pig  soon  dies  with  convulsions  in  a 
space  containing  a  small  amount  of  oxygen,  while  a  frog  will  remain 
alive  many  hours  in  a  space  quite  free  of  oxygen.  It  is  well  known 
that  fishes  and  aquatic  animals  generally  only  require  a  small  amount 
of  oxygen,  and  this  is  in  accordance  with  the  fact  that  sea-water  con- 
tains only  small  quantities  of  this  gas. 

Aquatic  breathers,  however,  if  they  live  in  a  medium  containing 
little  oxygen,  have  the  advantage  that  they  are  not  troubled  with  free 
carbonic  acid.  One  of  the  most  striking  facts  discovered  by  the  Chal- 
lenger chemists  is  that  sea-water  contains  no  free  carbonic  acid,  except 
in  some  situations  where  the  gas  is  given  off  by  volcanic  action  from  the 
crust  of  the  earth  forming  the  sea-bed.  In  ordinary  sea-water  there  is 
no  free  carbonic  acid,  because  any  carbonic  acid  formed  is  at  once  ab- 
sorbed by  the  excess  of  alkaline  bases  present.  Thus  the  fish  breathes 
on  the  principle  of  Fleuss's  diving  apparatus,  in  which  the  carbonic 
acid  formed  is  absorbed  by  an  alkaline  solution.  (See  British  Medical 
Journal,  No.  1442,  August  18,  1888.) 

The  organic  matters  contained  in  expired  air  are  small  in  quantity 
and  of  unknown  nature.  If  a  large  quantity  of  such  air  be  drawn 
through  distilled  water,  or  if  its  moisture  be  condensed  by  cold,  the 
liquid  thus  produced  contains  nitrogenous  matter,  has  a  peculiar 
unpleasant  odor,  and  usually  soon  putrifies.  The  free  air  also  contains 
combined  nitrogen  in  the  form  of  salts  of  ammonia  of  nitrous  or  nitric 
acid  and  of  organic  matters,  and  the  quantity  of  these  may  be 
approximately  determined  by  the  methods  for  determining  ammonia 
and  albuminoid  ammonia. 

An  account  of  the  various  methods  used  for  this  purpose  may  be 
found  in  a  report  on  the  subject  of  organic  matter  in  the  air  made  by 
Professor  Ira  Remsen,  and  published  in  the  National  Board  of  Health 
Bulletin,  Vol.  2,  1880,  p.  517. 

Professor  Remsen  drew  from  50  to  100  litres  of  the  air  to  be 
tested  through  a  tube  filled  with  coarsely-powdered  pumice  stone 
moistened  with  distilled  water.  When  the  measured  amount  of  air 
had  been  drawn  through  this,  the  pumice  stone  was  brought  into  a 
perfectly  clean  flask  and  500  cc.  of  distilled  water  added,  and  this 
water  was  then  tested  for  ammonia  and  albuminoid  ammonia  by  the 
usual  methods.  The  quantity  of  albuminoid  ammonia  thus  found  to 
be  derived  from  organic  matters  is  stated  to  be  per  1,000  cubic 


90  ORGANIC    MATTER    IN    AIR. 

meters  :  in  external  air  from  0.051  to  0.345  grams;  in  laboratory  air 
from  0.28  to  0.44  grams  ;  in  air  contaminated  by  respiration,  0.309  to 
0.339  grams.  His  conclusion  is  that  air  contaminated  by  respiration 
contains  more  than  the  usual  amount  of  albuminoid  ammcnia.  In  a 
paper  on  the  estimation  of  nitrogenous  organic  matter  in  air  (Lancet, 
1872,  Vol.  2,  p.  628-9),  W.  A.  Moss  reports  the  number  of  milligrams 
of  organic  matter  found  in  one  cubic  meter  of  air  to  be  in  the  external 
air  0.035  to  0.192;  in  hospital  wards  0.197  to  1.307;  in  a  privy  0.86,  and 
in  respired  air  o.i  to  0.54.  In  a  paper  on  analyses  of  air  published  in 
the  American  Chemical  Journal^  Vol.  i,  1879,  p.  263,  Mr.  Van  Slooten 
gives  the  results  of  some  determinations  made  in  New  Orleans  during 
the  epidemic  of  yellow  fever  in  1879  showing  from  25010  350  grains  of 
albuminoid  ammonia  per  million  cubic  feet  of  air  during  the  epidemic 
month  (September)  and  from  45  to  90  grains  during  November,  but  the 
reliability  of  his  work  is  questioned  by  Professor  Remsen,  The 
results  of  analyses  made  in  Glasgow  and  in  Paris  indicate  that  the  pro- 
portion of  ammonia  and  of  albuminoid  ammonia  increases  in  the 
winter  months. 

Experiments  have  been  made  by  Carnelley  and  Mackie  to  de- 
termine the  amount  of  organic  matter  in  undiluted  expired  breath. 
"  For  this  purpose  the  observer  inspired  the  air  of  the  room  through 
his  nose,  and  expired  through  the  mouth  into  a  closed  bottle  of  about 
3^  litres  capacity,  and  provided  with  a  small  outlet  tube  for  the  escape 
of  the  excess  of  expired  air.  This  bottle  was  maintained  at  a 
temperature  of  about  45°  C.  by  immersion  in  warm  water,  in 
order  to  prevent  condensation  of  moisture  from  the  breath.  When 
the  bottle  was  full  of  expired  air,  for  which  50  expirations  were  con- 
sidered sufficient,  the  temperature  of  the  enclosed  air  was  observed, 
the  inlet  and  outlet  tubes  closed,  and  the  bottle  removed  from  the  bath 
and  allowed  to  cool  down  to  the  temperature  of  the  room,  when  the 
inlet  tube  was  opened  and  air  allowed  to  enter  to  fill  the  partial 
vacuum.  The  temperature  of  the  enclosed  air  was  again  observed,  and 
the  amount  of  organic  matter  determined  in  the  usual  way.  A  deter- 
mination of  the  amount  of  organic  matter  in  the  air  of  the  room  was 
likewise  made  at  the  same  time.  The  proportion  of  expired  and  un- 
respired  air  of  the  room  in  the  bottle  could  be  found  by  calculation. 
Then,  by  deducting  from  the  total  organic  matter  that  present  in  the 
known  proportion  of  unrespired  air,  the  difference  gave  the  amount  of 
organic  matter  in  undiluted  breath.  Care  was  taken  to  breathe  as 
nearly  as  possible  in  a  natural  manner.  The  results  obtained  were  as 
follows: 


ORGANIC    MATTER    IN    AIR. 


OBSERVER  —  A. 

OBSERVER  —  B. 

Total  in 
Expired  Air. 

In  Air  of 
Room. 

Excess  in 
Expired  Air. 

Total  in 
Expired  Air. 

In  Air  of 
Room. 

Excess  in 
Expired  Air. 

3-3 
12.4 
5-8 
ii.  8 
15.6 

1.6 
3-2 
1.6 

2.2 
2.O 

1-7 
9.2 
4.2 
9.6 
13.6 

6.5 

12.2 
13.3 
I3.I 
10.  1 

3-0 
1.6 

4-7 
1.9 

2.3 

3-5 
10.6 
8.6 

II  .2 

7.8 

Average  p 

er  litre 

7.6 

Average  per  litre  .  . 

8.3       . 

The  above  determinations  were  mostly  made  on  different  days. 
According  to  these  experiments  the  amount  of  oxidizable  organic 
matter  in  breath  is  by  no  means  constant,  but  varies  from  time  to 
time,  nor  is  the  quantity  so  great  as  one  might  have  expected.  It  is 
possible,  however,  that  the  organic  matter  in  freshly  expired  r/Veath  is 
not  in  a  condition  to  readily  reduce  permanganate,  but  after  exposure 
for  some  time  in  the  air  it  may  undergo  such  a  change  as  will  render  it 
more  readily  oxidizable."* 

"  The  term  '  organic  matter,'  as  explained  by  the  authors,  is  a 
very  indefinite  orte,  and  really  signifies  the  bleaching  action  of  the  air 
on  a  dilute  solution  of  potassium  permanganate  acidified  with  sul- 
phuric acid.  It  therefore  includes  not  only  organic  matter  properly  so 
called,  but  those  substances  which  air  sometimes  contains,  such  as 
sulphuretted  hydrogen,  sulphurous  acid,  etc.,  which  also  bleach  per- 
manganate solution.  Even  the  organic  matter  itself  may  be  of  very 
different  kinds,  and  vary  considerably  as  regards  its  influence  upon 
health,  some  doubtless  being  quite  harmless,  whilst  some  may  exert  a 
very  deadly  effect.  In  so  far,  therefore,  as  the  method  does  not  dis- 
tinguish between  these  various  constituents  of  air,  but  brings  them  all 
into  the  same  category,  it  is  a  very  imperfect  method.  But,  as  no 
better  process  has  yet  been  devised,  it  is  the  only  one  which  has  been 
at  our  disposal."! 


*  Philosophical  Transactions  of  the  Royal  Society  of  London.     Vol.  178. 
(B)p.  87. 

f  Philosophical  Transactions  of  the  Royal  Society  of  London.     Vol.  178. 
(B)  p.  62. 


92  ORGANIC    MATTER    IN    AIR. 

The  following  table*  is  a  summary  of  the  results  obtained  from 
examination  of  the  air  in  the  streets,  schools  and  hospitals  in  Dundee 
and  Perth  during  the  winter  and  spring  of  1885-86,  by  Carnelley,  Hal- 
dane,  and  Anderson. 

The  carbonic  acid  is  stated  as  the  number  of  volumes  contained 
irn  10,000  of  air. 

The  organic  matter  is  stated  by -the  volume  of  oxygen  required  to 
oxidize  the  oxidizable  organic  matter  in  1,000,000  volumes  of  air. 

The  micro-organisms  are  represented  by  the  number  per  litre  of 
air  which  will  grow  on  Koch's  nutrient  jelly  kept  in  a  room  under 
ordinary  conditions. 


Carbonic 
Acid. 

Organic 
Matter. 

Total  Micro- 
organisms. 

It 
13 

Mean. 

Mean. 

Mean. 

With     2—  m  volumes  of  rarhonio.  arid 

2  7 

*  6 

I  Q 

s6 

4-6         "                     '•            " 

4  Q 

6  i 

•2    e 

27 

6-8                                                   

7.7 

IO  4 

2Q  7 

25 

8-10                                                   ... 

8.0 

Q     C 

•37    C 

26 

IO-I2                                                                     

ii.  i 

n  4 

79-6 

29 

12-15                                                   

13.3 

ii.  8 

36.3 

27 

15-20                                                       

17.0 

13.0 

I37.O 

31 

20-30                                                   .    .          .            ... 

22.9 

13.6 

82.0 

12 

30  and  above                                  

37.1 

19.8 

53.O 

9 

w 

th     0-2.8  vols,  oxygen  required  for  organic  matter 

4-3 

1.6 

5-3 

21 

2.8-  5.6 

6.8 

4-2 

10.  1 

52 

5.6-  8.4 

9-7 

7-2 

34-1 

58 

8.4-11.2 

10.7 

9-7 

29.2 

24 

11.2-14.0 

Il.Q 

12.6 

88.3 

31 

14.0-16.8 

16.6 

15-4 

57-1 

17 

16.8-22.4 

18,5 

19-3 

145.0 

17 

22.4  and  above 

18.8 

29.7 

87.0 

15 

In  1887-88,  Brown  Sequard  and  d'Arsonval,  reported  to  the 
Society  of  Biology  of  Paris,  that  as  the  result  of  repeated  experiments 
they  found  that  air  expired  from  the  lungs  contains  a  volatile  poison 
belonging  to  the  class  of  organic  alkaloids  and  resembling  in  its  effects 
a  ptomaine.  The  condensed  liquid  from  expired  air,  contains  this 
poison,  and  a  few  cubic  centimetres  of  it  injected  into  a  rabbit  pro- 
duced death. 

*  Philosophical  Transactions  of  the  Royal  Society  of  London.  Vol.  178. 
(B)  1888,  p.  86. 


ORGANIC    MATTER    IN    AIR.  93 

Somewhat  similar  results  had  been  obtained  by  previous  observers, 
by  enclosing  animals  in  glass  cases,  absorbing  the  carbonic  acid  pro- 
duced and  supplying  oxygen,  death  following  in  a  short  time. 

On  the  other  hand,  Hermann,  (Arch.  f.  Hyg.  I,  1883),  Dastre  and 
Loye  (Memoires  de  la  Soc.  de  biol.  1888-91),  and  others  report 
results  which  are  totally  contradictory  ot  those  mentioned  above, 
denying  that  the  condensed  fluid  has  any  toxic  qualities. 

Lehmann  &  Jessen  (Arch.  f.  Hygiene,  x,  p.  367),  state  as  a 
result  of  their  work  upon  this  subject : 

(1)  That  the  water  obtained  from  expired  air  by  condensation, 
when  unmixed  with  saliva  and  other  matters,  is  a  clear,  odorless  fluid, 
of  neutral  reaction,  in  which  traces  of  ammonia  and  hydrochloric  acid 
can  be  detected.     Upon  being  heated  it  gives  off  a  peculiar  odor.     It 
contains  a  smalL  portion  of  organic  matter,  but  poisonous  alkaloids 
could  not  be  detected  by  any  of  the  analytical  methods  at  their  dis- 
posal. 

(2)  The  only  crystallizable  bodies  detected  by  them,  were  crystals 
of  lime  which  came  from  the  walls  of  the  glass  apparatus  employed. 

(3)  Neither  the  condensed  vapor  nor  its  distillate,  when  injected 
either  subcutaneously  or  into  the  peritoneal  cavity  of  rabbits,  had  any 
effect  whatever,  though  large  doses  were  employed. 

(4)  Experiments  upon  human  beings  in  which  the  individual  was 
caused  to  inspire  air  that  had  passed  through  the  condensed  vapor  of 
expiration  were  entirely  without  toxic  results. 

The  matter  is  one  which  requires  much  more  investigation,  but  in 
the  meantime  it  is  certain  that  expired  air  contains  substances  which 
give  it  a  peculiar  odor,  which  produce  discomfort  and  a  feeling  of  op- 
pression when  present  in  quantity  in  air  inhaled — and  which,  when 
concentrated,  are  probably  dangerous,  and  the  cause  of  some  of  the 
bad  effects  due  to  overcrowding  and  insufficient  ventilation.  There 
appears  to  be  a  definite  relation  between  the  odors  caused  by  these 
substances  and  the  amount  of  carbonic  impurity  due  to  respiration 
present,  as  will  be  more  fully  explained  in  the  chapter  on  quantity  of 
air  desirable  for  ventilation.  These  substances  when  concentrated  and 
injected  into  the  blood  of  animals  may,  or  may  not,  kill  them— but  this 
proves  nothing  as  to  their  effects  when  inhaled  by  man.1 

A  certain  amount  of  carbonic  acid  and  large  quantities  of  watery 
vapor  are  exhaled  by  the  skin,  and  it  is  possible  that  a  small  amount  of 
oxygen  is  absorbed  through  the  skin,  but  the  gaseous  impurities  added 

1  See  for  a  critical  review  on  this  subject:  "  Sur  la  toxicite  de  1'air  expire,'* 
par  Dr.  Richard,  Rev.  d  hyg.,  1889,  XI.,  p.  338. 


94  EFFECTS   OF    HOT    AIR. 

to  the  air  from  the  skin,  are  small  in  amount  and  importance.  The 
particulate  matters  passing  into  the  air  from  the  skin  in  the  form  of 
epithelial  scales  are  of  more  importance — but  only  when  this  epithelium 
comes  from  diseased  bodies,  and  may  thus  be  the  means  of  co'nveying 
specific  causes  of  disease. 

By  measurement,  the  expired  air  is  found  to  be  greater  in  volume 
than  it  was  when  inspired.  This  is  due  in  part  to  its  expansion  under 
the  influence  of  increased  temperature,  and,  in  part,  to  the  additional 
amount  of  water  vapor  which  it  now  carries.  If,  however,  the  expired 
air  be  dried  and  reduced  to  the  same  conditions  of  temperature  as  it  had 
when  inspired,  we  shall  find  that  it  has  actually  lost  in  volume  ;  for  as 
we  saw  5. 4  per  cent,  by  volumeof  oxygen  is  taken  up  in  the  lungs,  and 
only  4.3  percent  by  volume  of  carbonic  acid  is  given  off  to  replace  it, 
making  a  loss  in  volume  in  each  100  parts  of  air  respired  of  i.i  percent. 
In  other  words,  for  every  100  parts  by  volume  of  air  inspired  (mea- 
sured under  normal  conditions  of  temperature  and  pressure),  only  99 
parts  are  expired — and  this  explains  the  discrepancy  in  the  two  formulae, 
in  which  the  composition  of  free  air  and  respired  air  are  compared.  Of 
the  alterations  found  to  take  place  in  the  air  as  a  result  of  being  breathed, 
perhaps  those  of  greatest  moment  in  the  case  of  overcrowded,  badly  ven- 
tilated apartments  are  the  rise  in  temperature  and  the  excessive  accu-  , 
mulation  of  watery  vapors.  As  a  result  of  these  changes  in  the  condition 
of  the  air,  the  heat-regulating  processes  of  the  body  are  more  or  less 
impeded,  and  in  extreme  cases  death  has  been  known  to  result. 

Not  unfrequently  the  co-existence  of  high  temperature  and  exces- 
sive relative  humidity  occurs  in  the  open  atmosphere,  and  it  is  just  at 
such  times  that  the  greatest  number  of  sun-strokes  are  observed. 

In  perfectly  dry  air  astonishingly  high  temperatures  may  be 
borne  without  any  marked  evil  effects,  for  here  the  heat  which  is  lost 
in  the  process  of  evaporation  from  the  surfaces  of  the  body  prevents  the 
internal  rise  of  temperature,  which  is  so  deleterious  to  the  proper 
functions  of  the  tissues.  Evaporation  is  here  favored  rather  than  re- 
tarded, and,  as  we  know  that  with  an  increase  in  evaporation  more  heat 
is  required,  it  is  plain  that  so  long  as  this  hot  air  is  dry,  there  is  but 
little  fear  of  any  marked  rise  of  temperature  in  the  body. 

If,  however,  this  hot  air  is  charged  with  a  large  amount  of 
moisture  we  find  a  decided  obstruction  to  evaporation,  the  obstruction 
being  proportionate  to  the  amount  of  water  already  present  in  the  air. 

Under  such  conditions  the  cooling  effect  of  evaporation  from  the 
surfaces  is  greatly  diminished  and  there  is,  in  consequence,  a  rise  of  in- 
ternal temperature.  With  the  rise  of  body-temperature  the  chemical 


BLACK    HOLE    OF    CALCUTTA.  95 

changes  which  are  going  on  in  the  tissues,  become  more  and  more  ex- 
aggerated until  they  reach  a  point  quite  incompatible  with  life.  Ex- 
periments upon  lower  animals  have  demonstrated  that  life  ceases  when 
the  temperature  of  the  tissues  reaches  120°  F.  (49°  C.),the  approach  of 
death  being  announced  by  beginning  rigidity  of  the  muscles. 

The  "black  hole"  of  Calcutta  is  an  extreme  instance  of  this  co- 
existence of  high  temperature  and  excess  of  moisture  in  the  air  of  an 
enclosed  apartment. 

On  the  capture  of  Fort  William  in  Calcutta,1  in  1756,  by  the 
Nawab  of  Bengal,  the  Europeans  who  remained  surrendered,  and 
were  driven  at  the  point  of  the  sword  into  the  guard  room,  a 
chamber  scarcely  20  feet  square,  with  but  two  small  windows, 
which  were  strongly  barred  with  iron.  Into  this  on  a  sultry  night, 
146  men  were  pressed,  giving  to  each  an  area  of  less  than  18 
inches  square.  Very  soon  after  they  were  crowded  in,  an  almost  in- 
credibly profuse  perspiration  broke  out  upon  them,  which  was  followed 
by  consuming  and  increasing  thirst.  They  became  furious  and  loaded 
the  guards  with  insults  to  provoke  them  to  fire,  in  which  they  failed. 
They  made  most  furious  cries  for  water  ;  a  little  of  it  was  brought  to 
them  in  hats  and  forced  through  the  bars.  The  stronger  forced  their 
way  to  the  window  and  bore  down  and  trampled  to  death  the  weaker 
ones.  By  half-past  eleven  most  of  the  living  were  outrageous  and  the 
others  quite  ungovernable.  At  six  in  the  morning  the  order  arrived 
for  their  release.  At  that  time  only  23  were  left  alive,  and  so  ex- 
hausted were  the  survivors  that  more  than  20  minutes  elapsed  before 
they  could  remove  the  dead  from  the  door  so  they  could  make  suffi- 
cient opening  to  pass  out  one  at  a  time.  Most  of  those  who  survived 
were  affected  with  a  form  of  fever  resembling  typhoid,  which  was 
followed  by  an  eruption  of  large  and  painful  boils. 

Somewhat  similar  results  occurred  on  the  steamer  "Londonderry," 
when  150  passengers  were  confined  in  a  small  cabin  for  several  hours, 
and  70  of  them  died. 

Another  source  of  gaseous  pollution  for  the  air  of  dwellings  is  the 
material  employed  in  their  illumination.  As  a  result  of  the  combus- 
tion of  the  ordinary  illuminating  agents,  quite  a  group  of  volatile 
bodies  are  given  off — their  nature  and  amount  depending  largely 
upon  the  nature  of  the  material  employed  and  the  completeness  of 
combustion. 

1Howell,  John  S.,  Relation  of  the  deplorable  death  of  English  and  other 
persons  suffocated  in  the  Black  Hole  at  Fort  William,  Calcutta,  etc.  London, 
1756,  8vo. 


96  BACTERIA    IN    AIR. 

The  most  conspicuous  changes  wrought  in  the  air  in  which  gas  or 
oil  (for  the  products  of  both  are  about  the  same)  are  burned  are  eleva- 
tion in  temperature,  the  addition  of  water-vapor,  carbon  monoxide, 
carbon  dioxide,  nitric  and  nitrous  acid,  compounds  of  ammonia  and  of 
sulphur,  marsh  gas,  carbon  particles  and  acids  of  the  fatty  group. 
Aside  from  the  gases  given  off  as  products  of  combustion  in  the 
process  of  illumination,  it  must  be  borne  in  mind  that  for  produc- 
ing combustion  a  certain  amount  of  oxygen  is  needed,  for  which 
the  burning  material  must  draw  upon  the  stock  in  the  dir  of  the 
apartment. 

In  the  case  of  gas  an  ordinary  small  burner  will  burn  about  3 
cubic  feet  per  hour,  or  in  an  evening  of  four  hours  from  10  to  12  cubic 
feet.  Approximately  the  burning  of  each  cubic  foot  of  gas  requires 
1. 12  cubic  feet  of  oxygen,  or  5.33  cubic  feet  of  air,  so  that  for  the 
above  interval  of  four  hours  about  64  cubic  feet  of  air  would  be 
required  for  the  combustion  alone  of  the  gas  from  a  single  burner,  to 
say  nothing  of  the  amount  that  should  be  supplied  in  order  to  dilute  the 
gaseous  products  from  this  burner  to  a  point  at  which  they  could  not  be 
appreciated.  It  will  be  seen,  then,  where  illumination  by  means  of  burn- 
ing substances,  as  gas,  oil,  fats,  etc.,  is  employed  on  a  large  scale,  its 
effect  must  be  considered  in  calculating  for  the  amount  of  ventilation 
necessary.  In  small  apartments,  however,  it  is  generally  conceded 
that  if  the  amount  of  day  ventilation  is  properly  calculated,  no 
increase  to  cover  the  requirements  of  illumination  will  be  necessary. 

The  subject  will  be  gone  into  more  in  detail  in  the  chapter  on 
"  Calculation  of  amount  of  ventilation  necessary  under  different  cir- 
cumstances." 

Beside  deleterious  gases  and  accumulation  of  water-vapors,  cer- 
tain solid  matters  are  found  in  the  air  of  apartments. 

As  was  demonstrated  by  Tyndall,  the  coarser  of  these  solid 
matters  floating  in  the  air  may  be  seen  dancing  in  a  ray  of  sunlight 
admitted  to  a  darkened  chamber.  For  the  most  part  these  objects  are 
harmless  bits  of  inorganic  dust  due  to  the  wear  and  tear  upon  floors, 
furniture  and  hangings  of  the  room.  Upon  some  of  these  dust  par- 
ticles, however,  are  deposited  microscopic  living  plants,  which  possess 
biological  characteristics  quite  as  distinctive  as  those  seen  in  the 
different  members  of  the  animal  kingdom.  These  very  small  plants 
belong  to  the  family  of  Bacteria.  They  have  a  variety  of  physiological 
functions,  some  of  them  being  concerned  in  specific  fermentative 
changes,  others  giving  rise  to  what  we  recognize  as  decomposition,  a 
large  number  having  the  power  of  producing  brilliant  pigment  pro- 


BACTERIA    IN    AIR.  97 

ducts,  and  perhaps  the  smallest  group  being  those  directly  concerned 
in  the  causation  of  disease. 

To  most  people  the  word  "  bacteria,"  almost  without  exception,  is 
connected  with  disease.  Such  an  idea  is  erroneous.  The  vast  majority 
of  the  members  cf  the  group  of  organisms  are  our  benefactors,  and  only 
a  very  small  proportion  of  them  are  directly  concerned  in  the  produc- 
tion of  disease.  The  non-pathogenic  varieties  (those  incapable  of  pro- 
ducing disease)  are  of  a  purely  saprophytic  nature — that  is,  they  exist 
upon  dead  matters — either  vegetable  or  animal. 

"  The  role  played  in  nature  by  the  saprophytic  bacteria  is  a  very 
important  one.  Through  their  presence  the  highly  complicated  tissues 
of  dead  animals  and  vegetables  are  resolved  into  the  simpler  com- 
pounds, carbonic  acid  and  ammonia,  in  which  form  they  may  be  taken 
up  and  appropriated  as  food  by  the  more  highly  organized  mem- 
bers of  the  vegetable  kingdom.  It  is  by  this  ultimate  production  of 
carbonic  acid,  ammonia,  and  water  by  the  bacteria,  as  end-products  in 
the  processes  of  decomposition  and  fermentation  of  the  dead  animal 
and  vegetable  tissues,  that  the  demands  of  growing  vegetation  for 
these  compounds  are  largely  supplied. 

The  chlorophyl  plants  do  not  possess  the  power  of  obtaining  their 
carbon  and  nitrogen  from  such  highly  organized  and  complicated  sub- 
stances as  serve  for  the  nutrition  of  the  bacteria,  and  as  the  produc- 
tion of  the  simpler  compounds  (CO2,  NH3,  H2O)  by  the  animal 
world  'is  not  sufficient  to  meet  the  demands  of  the  chlorophyl  plants, 
the  importance  of  the  part  played  by  the  bacteria  in  making  up  this 
deficit  cannot  be  overestimated.  Were  it  not  for  the  activity  of  these 
microscopic  living  particles,  all  life  upon  the  surface  of  the  earth  woul£-- 
certainly  cease.  Deprive  higher  vegetation  of  the  carbon  and  nitrogen 
supplied  to  it  as  a  result  of  bacterial  activity,  and  its  development 
comes  rapidly  to  an  end.  Rob  the  animal  kingdom  of  the  food-stuffs* 
supplied  to  it  by  the  vegetable  world,  and  life  is  no  longer  possible. 

Were  it  not  for  the  presence  of  these  saprophytic  forms,  the  sur- 
face of  the  earth  w6uld  in  course  of  time  be  strewn  with  the  remains 
of  dead  animals  and  vegetables. 

Another  group,  the  water  bacteria,  are  perhaps  instrumental  in 
bringing  about  favorable  changes  in  polluted  waters.  Still  others  are 
concerned  in  the  production  of  changes  in  the  soil  which  favor  the  life 
of  higher  members  of  the  vegetable  kingdom. 

It  is  plain,  therefore,  that  the  saprophytes,  which  represent  by  far 
the  large  majority  of  all  bacteria,  must  be  looked  upon  by  us  in  the 
light  of  benefactors,  without  which  existence  would  be  impossible. 


98  BACTERIA    IN    AIR. 

With  the  parasites,  on  the  other  hand,  the  conditions  are  fair  from 
analogous.  Through  their  existence  there  is  constantly  a  loss,  rather 
than  a  gain,  to  both  the  animal  and  vegetable  kingdoms.  Their  host 
must  always  be  a  living  body  in  which  exist  conditions  favorable  to 
their  development,  and  from  which  they  appropriate  substances  which 
may  be  necessary  to  the  health  and  life  of  the  tissues  of  the  organism  to 
which  they  may  have  found  access.  At  the  same  time  the  substances 
which  they  form  as  products  of  their  nutrition  may  be  direct  poisons 
for  surrounding  tissues. 

In  their  relations  to  humanity  the  positions  occupied  by  the  two 
biologically  different  groups,  the  saprophytes  on  the  one  hand  and  the 
parasites  on  the  other,  are  directly  opposite;  the  saprophytic  forms 
standing  in  the  relation  of  benefactors,  in  resolving  dead  animal  and 
vegetable  bodies  into  their  component  parts,  which  serve  for  food  for 
living  vegetation,  and,  at  the  same  time,  removing  from  the  surface  of 
the  earth  the  remains  of  all  dead  organic  substances;  while  the  para- 
sitic group  exists  only  at  the  expense  of  the  more  highly  organized 
members  of  both  kingdoms.  It  is  to  the  parasitic  group  that  the  patho- 
genic organisms  belong.  ("  The  Principles  of  Bacteriology,"  Abbott, 
pp.  23  and  24). 

As  has  been  said,  bacteria,  as  a  rule,  are  found  in  the  air  deposited 
upon  dust  particles,  and  it  follows,  therefore,  that  where  dust  is  most 
.abundant,  there  bacteria  are  likely  to  be  present  in  largest  numbers- 
This  dust,  if  found  in  the  open  streets  or  ordinary  dwelling  houses,  is 
not  of  necessity  dangerous  because  of  the  bacteria  associated  with  it; 
but  if  it  is  found  in  the  apartments  of  a  patient  suffering  from  some 
infectious  malady,  it  can  hardly  be  considered  as  of  such  an  innocent 
nature.  Recent  experiments  show  that  infection  may  be  carried  by 
the  dust  of  apartments  occupied  by  persons  suffering  from  infectious 
diseases.  Especially  is  this  the  case  with  the  dust  of  rooms  occupied 
by  consumptives,  and  particularly  so  when  they  are  not  cleanly  in  their 
habits.  Here  the  expectoration,  in  which  the  organism  causing  the 
disease  may  always  be  found,  is  not  unfrequently  allowed  to  dry  upon 
the  napkins,  handkerchiefs,  or  clothing  of  the  patient,  or  when  it  finds 
its  way  to  the  floor,  it  may  be  ground. up  with  the  dust  into  powder  by 
the  feet  of  those  walking  about  the  room.  In  this  form  it  may  readilv 
become  suspended  in  the  air  and  be  inhaled  by  other  occupants  of  the 
apartment.  The  frequency  of  the  pulmonary  form  of  consumption  can 
most  probably  be  explained  in  this  way.  The  organisms  causing 
erysipelatous  inflammations  have  been  found  in  the  dust  from  beneath 
the  floor  of  a  room  occupied  by  persons  suffering  from  erysipelas. 


BACTERIA    IN    AIR.  99 

The  pyogenic  micrococci  (the  organisms  giving  rise  to  abscesses 
and  other  pus  formations)  are  not  uncommonly  present  in  the  air  of 
apartments  occupied  by  patients  suffering  from  suppurative  troubles. 

It  is  safe  to  say  that  under  normal  conditions  the  chances 
of  finding  disease-producing  organisms  in  the  air  of  apartments 
are  not  very  great.  If,  however,  the  apartment  be  occupied  by  patients 
undergoing  treatment  for  infectious  troubles,  their  demonstration  may 
be  possible,  more  particularly  in  the  dust,  but  where  cleanliness  and 
the  prevention  of  the  accumulation  of  dust  is  carried  out,  the  air  may 
be  kept  practically  free  from  bacteria. 

To  recapitulate,  the  alterations  experienced  by  the  air  of  over- 
crowded, poorly  ventilated  apartments,  as  a  result  of  life  processes,  are: 

(i.)  A  slight  diminution  in  the  amount  of  oxygen. 

(2.)  An  increase  in  the  amount  of  carbonic  acid,  and  along  with  it 
the  organic  pollution  resulting  from  the  decomposition  of  perspiration 
and  epithelium  on  the  surface  of  the  body,  and  from  gastric  and  intes- 
tinal digestion  and  decomposition. 

(3.)   Elevation  of  its  temperature  and  addition  of  moisture. 

(4.)  The  addition  of  solid  particles,  upon  which  may  be  deposited 
either  innocent  or  disease-producing  bacteria,  for  the  most  part  the 
former. 

We  will  now  consider,  briefly,  some  of  the  impurities  of  air  due, 
not  to  respiration  or  to  cutaneous  exhalation  or  exfoliation,  but  to  certain 
conditions  connected  with  human  habitations  or  occupations,  including 
sewer  air,  coil  air,  offensive  and  dangerous  gases  due  to  various  pro- 
cesses of  manufacture,  and  dusts  of  the  same  origin. 

Sewer  air,  including  not  only  the  air  of  sewers  properly  so-called, 
but  the  air  of  house  drains  and  cesspools,  has  been  the  subject  of 
much  literature  and  of  many  discourses  during  the  last  40  years,  and 
the  dangers  of  "  sewer  gas,"  as  it  has  been  called,  have  been  brought 
to  the  attention  of  the  public  so  frequently  and  so  forcibly  as  to  have 
produced  in  many  places  special  laws  and  municipal  regulations  with 
regard  to  house  drainage. 

The  origin  or  spread  of  between  30  and  40  different  diseases, 
including  small  pox,  scarlet  fever,  measles,  malaria,  diphtheria, , 
typhoid,  inflammations  of  the  ear,  eye,  throat,  etc.,  dyspepsia,  diar- 
rhceal  affections,  coughs,  colds,  lung  diseases,  liver  affections  and  skin 
troubles  has  been  from  time  to  time  attributed  to  this  so-called  "sewer 
gas,"  and  much  labor  has  been  expended  in  efforts  to  isolate  this 
poison  and  determinine  its  composition  and  properties.  We  are  now 
fairly  well  acquainted  with  the  composition  of  the  air  found  in  sewers, 


100  SEWER  AIR. 

and  know  that  there  is  no  such  thing  as  a  distinct  and  peculiar  sewer 
gas.  The  air  of  ordinary  sewers  and  house  drains  is  ordinary  atmos- 
pheric air,  mixed  with  a  relatively  small  amount  of  gases  and  vapors 
due  to  decomposition  of  sewage  and  also  containing  micro-organisms 
suspended  in  it,  which  are,  as  a  rule,  the  same  as  those  contained  in 
the  air  of  streets,  but  in  less  number  for  a  given  volume  of  the  air. 
The  products  of  the  decomposition  of  sewage  are  carbonic  acid,  light 
carburetted  hydrogen,  sulphuretted  hydrogen,  ammonium  sulphide, 
ammonium  carbonate  and  volatile  organic  matters,  the  precise  charac- 
ter depending  not  only  on  the  composition  of  the  sewage  itself,  which 
varies  greatly,  but  on  the  nature  of  the  micro-organisms  at  work, 
which  depends  on  the  proportion  of  oxygen  present.  In  closed  cess- 
pools and  privy  vaults  and  in  foul  sewers  of  deposit,  which  are  practi- 
cally elongated  cesspools,  these  products  may  accumulate  to  such  an 
extent  that  the  mixture  produces  insensibility  and  asphyxia  in  those  who 
enter  it  and  may  rapidly  cause  death,  while  in  somewhat  less  concentrated 
form  they  cause  nausea,  diarrhoea  and  general  prostration  and  languor. 
The  air  of  sewers  is  also  liable  to  become  contaminated  with 
illuminating  gas  passing  in  through  the  soil  from  leaky  gas  pipes  in  the 
vicinity,  and  ultimately  producing  a  mixture  which  will  explode  if  a 
light  is  brought  into  it,  but  this  is,  of  course,  exceptional.  The  air  of 
an  ordinary  modern,  fairly  well  constructed  and  ventilated  sewer 
appears  to  differ  from  the  street  air  chiefly  in  having  a  higher  propor- 
tion of  carbonic  acid.  Thus  Professor  Nichols  reports  as  the  result  of 
a  large  number  of  analyses  of  the  air  in  a  six-foot  brick  sewer  3,500 
feet  long,  with  four  perforated  manholes  at  intervals,  that  the  propor- 
tion of  carbonic  acid  ranged  from  8.65  to  23.95  volumes  in  10,000  of 
air,  the  higher  proportion  occurring  in  the  warm  months.  This  was  a 
tide-locked  sewer,  and  the  ventilation  was  poor.  In  a  paper  on  the 
air  of  sewers  published  in  the  Proceedings  of  the  Royal  Society  of 
London,  Vol.  XLII.,  1847,  p.  51,  Carnelley  and  Haldane  give  the 
results  of  a  number  of  examinations  of  sewer  air  from  London  and 
from  Dundee  sewers,  in  which  the  carbonic  acid,  the  organic  matter 
and  the  number  .of  micro-organisms  were  determined.  They  found 
that  the  amount  of  CO2  was  about  twice,  and  of  organic  matter  about 
three  times  as  great  as  in  the  outside  air  at  the  same  time,  but  that  the 
number  of  micro-organisms  was  less,  that  as  regards  quantity  of  the 
three  constituents  named  the  air  of  the  sewers  was  in  a  very  much 
better  condition  than  that  of  naturally  ventilated  schools,  and  that 
with  the  notable  exception  of  organic  matter,  it  had  likewise  the  advan- 
tage of  mechanically  ventilated  schools. 


SEWER    AIR.  101 

A  special  attempt  was  made  to  separate  any  poisonous  volatile 
organic  bases  in  the  air  such  as  ptomaines,  but  without  success. 
The  majority  of  the  micro-organisms  found  come  from  the  outside 
air,  and  the  greater  the  proportion  of  carbonic  acid  the  fewer  of 
these  organisms  are  found.  Where  splashing  occurs  in  the  sewer  the 
number  of  micro-organisms  in  the  air  increases. 

Essentially  the  same  results  have  been  obtained  by  other  investi- 
gators making  bacterial  analyses  of  air.  Specific  pathogenic  micro- 
organisms have  not  been  found  in  the  air  of  sewers,  and  if  the 
sewers  are  properly  constructed  and  ventilated,  there  seems  to  be 
little  or  no  danger  in  remaining  in  them  for  several  hours.  As  regards 
house  drains  and  soil  pipes,  the  condition  of  the  air  in  them  depends 
greatly  upon  whether  they  are  properly  ventilated  or  not.  So  long  as 
the  fixtures  connected  with  them  are  in  daily  use  these  pipes  are  lined 
with  a  moist  slimy  layer  of  organic  matter,  in  which  bacteria  of  various 
kinds  grow  in  immense  numbers.  If  the  supply  of  air  is  abundant, 
these  bacteria  are  mostly  aerobic  and  the  substances  produced  by  their 
action  are,  as  a  rule,  odorless,  and  are  rapidly  carried  away,  by  the  air 
current,  if  gaseous,  by  the  next  flush  of  liquid,  if  soluble. 

As  bacteria  are  not  given  off  to  the  air  from  fluids  or  moist 
surfaces,  few  micro-organisms  are  to  be  found  in  soil  pipe  air,  and 
those  are  brought  in  from  the  external  air. 

It  will  be  seen  that  the  probabilities  of  the  conveyance  of  the 
germs  of  specific  diseases  through  sewer  or  soil  pipe  air  under 
ordinary  circumstances  are  very  small,  and  there  is  very  little  evidence 
that  any  diseases  have  been  thus  conveyed,  with  the  exception  of 
those  due  to  the  micro-organisms  which  produce  suppuration.  In 
hospitals,  before  the  introduction  of  antiseptic  methods  of  treatment  of 
wounds,  the  pyogenic  organisms  were  of  course  very  numerous  in  the 
hospital  drains,  and  there  are  several  cases  in  which  localized  outbreaks 
of  erysipelas  and  unhealthy  wound  action  appeared  to  be  connected  with 
the  passage  of  the  house  drain  air  into  the  ward. 

A  sufficient  number  of  cases  of  pyogenous  diseases  occurring  in 
persons  occupying,  in  the  autumn,  houses  which  had  stood  empty  all 
summer  have  also  been  reported  to  make  it  probable  that  when  the 
traps  become  empty  and  the  soil  pipes  dry,  some  infectious  dusts  may 
have  been  borne  into  the  rooms. 

Distinguished  English  sanitarians  believe  that  typhoid  fever  has 
been  spread  through  the  gases  coming  from  foul  sewers,  and  I  do 
not  deny  the  possibility,  but  I  know  of  no  satisfactory  evidence  of 
such  an  occurrence.  Diphtheria  and  typhoid  are  diseases  which 


IO2  SOIL    AIR. 

prevail  more  extensively  where  there  are  no  sewers  than  in  the 
sewered  part  of  the  cities,  even  where  the  sewers  are  badly  con- 
structed. 

While  I  do  not  attach  much  importance  to  sewer  air  as  a  means 
of  transmission  of  specific  disease,  I  believe  that  its  continuous  in- 
halation is  dangerous,  owing  to  the  large  amount  of  volatile  organic 
matters  which  it  contains,  and  that  for  this  reason,  as  well  as  to  prevent 
the  formation  of  explosive  mixtures  and  of  unpleasant  odors,  con- 
tinuous ventilation  should  be  provided  for  all  sewers,  house  drains  and 
cesspools.  The  methods  of  doing  this  will  be  described  hereafter. 

Another  source  of  atmospheric  pollution  is  the  ground.  Though  the 
air  of  the  soil  is  primarily  the  atmospheric  air  that,  through  processes 
of  diffusion  and  pressure  has  entered  the  pores  of  the  earth,  still  as 
we  find  it  there  it  has  undergone  such  manifold  changes  in  its  chemical 
composition  that  it  can  hardly  be  recognized.  The  most  conspicuous 
of  these  changes  result  from  the  activity  of  countless  living  micro- 
organisms that  are  present  in  the  superficial  layers  of  the  earth's  surface. 
Their  function  is  mainly  the  decomposition  of  highly  complicated 
organic  compounds  into  simpler  forms  in  which  condition  they  may 
be  taken  up  and  appropriated  as  nutrition  by  higher  plants.  In  per- 
forming these  functions  much  of  the  oxygen  of  the  air  is  used  up  by 
the  bacteria,  and  one  of  the  conspicuous  alterations  that  atmospheric 
air  is  seen  to  undergo  in  the  ground  is  a  marked  diminution  in  its  nor- 
mal amount  of  oxygen.  At  a  very  short  distance  below  the  surface 
the  reduction  in  the  amount  of  this  gas  has  produced  a  proportion  as 
low  as  7.4  parts  per  100  of  air,  instead  of  about  21  parts  per  100  as 
seen  in  the  atmosphere.  The  proportion  of  oxygen  thus  lost  is  used 
up  by  the  micro-organisms  in  processes  of  fermentation  and  decomposi- 
tion and  appears  again  in  the  products  of  these  processes,  and  we  find 
that  carbonic  acid  is  always  present  in  the  soil  air  in  greater  amounts 
than  in  the  free  atmosphere,  and  usually  in  much  greater  amounts.  As  a 
result  of  many  analyses  made  upon  the  air  of  the  ground,  carbonic  acid  is 
found  to  be  present  in  amounts  varying  from  0.2  per  cent,  to  14.0  per 
cent,  instead  of  0.04  per  cent,  as  in  the  normal  atmosphere.  Pettenkofer 
believes  the  fluctuations  in  the  amount  of  the  gas  in  the  soil  to  be  more 
or  less  parallel  with  fluctuations  in  temperature,  and  Moller  &  Wallney 
state  that  the  largest  amounts  of  carbonic  acid  are  found  in  soils  that 
are  rich  in  organic  matter,  moderately  moist,  of  a  suitable  temperature 
and  to  which  air  has  free  access. 

Another  gaseous  constituent  of  ground  air  that  appears  as  a  result 
of  decomposition  and  fermentation  is  ammonia.  This  compound  is 


SOIL    AIR.  103 

usually  present,  but  in  the  form  of  free  ammonia  in  only  very  small 
amounts.  Fodor,  as  a  result  of  many  analyses,  found  free  am- 
monia in  air  from  the  soil  to  the  extent  of  only  0.000048  to  0.000082 
grains  in  100  litres  of  air. 

Sulphuretted  hydrogen  can  also  at  times  be  demonstrated  in 
ground  air.  It,  too,  appears  as  a  product  of  decomposition  of  organic 
substances,  and  now  and  then  as  a  reduction  product  from  salts  of 
sulphuric  acid  (Soyka).  In  addition  to  these  commoner  gases  of  de- 
composition, some  of  the  carbon  compounds  have  been  found  in  ground 
air  by  Nichols,  and  Hoppe-Seyler  mentions  the  development  of  meth- 
ane in  a  piece  of  ground  saturated  with  moisture. 

Moisture  in  the  soil  is  so  essential  to  decomposition  and  nitrifica- 
tion that  without  it  these  phenomena  cannot  occur,  for  in  the  dry  state 
the  living  organisms  cannot  perform  their  functions. 

On  the  other  hand,  too  much  moisture,  complete  saturation,  is  also 
quite  as  much  of  an  obstacle  to  the.  existence  of  these  processes  as  no 
moisture  at  all.  It  is  in  ground  that  is  alternately  wet  and  dry,  speaking 
loosely,  that  the  organisms  find  the  most  favorable  conditions  for  their 
biological  activities,  and  it  is  in  just  such  soil  as  this  that  the  ordinary 
gaseous  products  are  found  in  greatest  abundance.  It  is  this  character 
of  ground  that  makes  up  the  greater  portion  of  the  earth's  surface. 

It  is  impossible  to  give  a  fixed  formula  for  the  air  of  the  soil, 
because  of  the  great  variations  that  are  seen  to  occur  in  the  relative 
proportion  of  its  constituents  in  air  taken  from  the  soil  of  different 
localities.  Analyses  made  of  air  from  points  in  the  ground,  closely 
located  the  one  to  the  other,  will  often  demonstrate  striking  differ- 
ences in  composition. 

In  general,  it  may  be  said  that  the  air  of  virgin  soil  is  more  con- 
stant in  its  composition,  and  freer  from  offensive  and  perhaps  harmful 
ingredients,  than  the  air  from  soils  round  about  the  habitations  of  man. 

This  difference  is  not  difficult  to  understand  if  one  compares  the 
conditions  found  in  virgin,  unoccupied  soil  with  those  seen  in  the 
ground  upon  which  great  cities  are  built.  Permeated,  as  the  latter  is  in 
all  directions  by  gas  mains  and  sewers  that  are  frequently  leaky,  con- 
taminated at  many  points  by  decomposing  waste  products  and  human 
excrement,  we  would  expect  to  find  a  condition  of  the  soil  air  quite  in 
contrast  with  that  of  ground  not  so  polluted,  and  so  we  do.  If,  in 
addition,  it  is  remembered  that  each  house  built  upon  such  soil 
acts  the  year  round  as  an  aspirator  for  the  air  of  the  ground  upon 
which  it  stands,  the  advantages  to  be  gained  by  proper  attention  to  the 
sanitary  condition  of  the  ground  are  plain.  The  air  thus  drawn  from 


104  OFFENSIVE    AND    DANGEROUS    GASES. 

the  soil  into  houses  not  only  contains  gaseous  ingredients  which  may 
or  may  not  be  deleterious  to  health,  but  it  is  wanting  in  oxygen,  the 
element  most  essential  to  the  healthy  performance  of  our  bodily 
functions. 

As  to  the  presence  of  bacteria  in  the  air  of  the  soil,  it  suffices  to 
say  that  analyses  of  air  drawn  from  the  soil  under  proper  precautions, 
show  it  to  be  free  from  living  organisms.  Though  bacteria  are  present 
in  countless  numbers  in  the  upper  layers  of  the  soil  itself  they  are 
nevertheless  held  there,  being  deposited  in  the  finer  pores,  and  caused 
to  adhere  through  the  moisture  that  surrounds  them. 

Under  normal  conditions  they  are  not  found  at  a  depth  greater 
than  i%  meters  (C.  Fraenkel),  and,  as  said,  have  not  been  detected  in 
the  air  from  the  ground. 

OFFENSIVE    GASES. 

The  gaseous  pollutions  arising  as  a  result  of  the  industries,  can 
hardly  be  considered  in  relation  to  the  air  of  private  apartments,  except 
perhaps  of  those  situated  in  the  immediate  vicinity.  For,  as  pointed 
out,  the  diffusion  and  mixing  of  gases  in  the  atmosphere  due  to  the 
action  of  the  winds,  is  so  rapid,  that  only  in  exceptional  instances 
can  the  polluting  matters  be  detected.  They  are  rapidly  swept  away 
from  their  source  by  the  air  currents  and  quickly  diluted  to  a  point 
that  renders  their  detection  a  matter  of  considerable  difficulty. 

In  the  immediate  neighborhood  of  certain  industries,  gases,  char- 
acteristic of  the  work  in  progress,  may,  under  favorable  atmospheric 
conditions,  sometimes  be  detected. 

In  some  instances  the  pollutions  have  only  the  etfect  of  diluting 
the  oxygen  in  the  air,  they  themselves  having  no  deleterious  action 
whatever  and  being  generally  considered  as  physiologically  neutral 
or  indifferent  substances.  For  example,  the  excess  of  hydrogen  and 
"  choke-damp,"  found  in  the  air  of  mines,  is  of  more  significance  in 
diminishing  the  ratio  of  oxygen  in  .the  air  breathed  than  of  producing, 
per  se,  any  direct,  definite  effect  upon  the  health  of  those  inhaling  it. 

On  the  other  hand,  from  certain  of  the  industries  where  products, 
chemical  in  nature,  are  manufactured,  or  where  they  are  of  such  a  com- 
position that  large  quantities  of  chemical  agents  are  employed  in  their 
production,  gases  of  a  deleterious  nature  are  not  uncommonly  thrown 
off  into  the  atmosphere. 

The  gaseous  waste  products  of  some  of  the  industries  as  given  by 
Parkes,  are  : 

Hydrochloric  acid  gas  from  alkali  works. 


OFFENSIVE    AND    DANGEROUS   GASES.  105 

Sulphur  dioxide  and  sulphuric  acid,  from  copper  works. 

Sulphuretted  hydrogen,  from  several  chemical  works,  especially 
from  ammonia  works. 

Carbon  dioxide,  carbon  monoxide  and  sulphuretted  hydrogen, 
from  brick  and  cement  works. 

Carbon  monoxide  (in  addition  to  above  cases),  from  iron  furnaces, 
may  amount  to  as  much  as  22  to  25  per  cent. ;  from  copper  furnaces, 
15  to  19  per  cent. 

Organic  vapors,  from  glue  refineries,  bone  burners,  slaughter 
houses  and  knackeries.  v 

Zinc  fumes,  from  brass  founderies. 

Arsenical  fumes,  from  copper  smelting  works. 

Phosphorous  fumes,  from  match  factories. 

Carbon  disulphide,  from  India-rubber  works. 

From  this  list  it  may  be  seen  that  the  most  of  these  waste  products 
are  not  only  of  an  offensive  character,  but  are  actually  irrespirable  in 
their  nature;  producing  in  some  instances  irritation  of  the  air  passages 
in  others  direct  systemic  poisonous  effects. 

As  directly  poisonous  products  of  the  industries  carbon  monoxide, 
sulphureted  hydrogen  and  the  compounds  of  carbon  and  sulphuric  acid 
may  be  mentioned,  less  frequently  arseniureted  and  phosphureted 
hydrogen,  and  the  vapors  of  iodine  and  of  bromide  may  be  detected. 

This  is  hardly  the  place  to  enter  into  a  discussion  upon  the 
gaseous  waste  products  from  special  industries;  it  suffices  to  say  that 
round  about  the  most  of  them,  certain  of  the  above-mentioned  com- 
pounds may  be  detected,  the  amount  present  depending,  of  course, 
upon  the  rate  of  production  and  the  efficacy  of  the  arrangements  for 
their  removal  or  destruction. 

It  is  safe  to  say  that  the  greater  influence  upon  health  from  the 
respiration  of  these  gases  is  experienced  by  those  immediately  engaged 
in  the  manufactories,  and,  unless  favored  by  particular  conditions  of 
wind  and  weather,  in  most  instances  the  presence  of  the  gases  in  the 
open  air  is  not  recognized  by  persons  outside  the  walls  of  the 
factories  in  which  they  are  produced. 

For  their  removal  from  the  work-rooms,  special  arrangements  are 
made,  which  will  be  referred  to  hereafter. 

In  the  free  atmosphere,  the  presence  of  dust  to  any  considerable 
amount,  is  only  an  intermittent  and  temporary  occurrence,  so  that  its 
significance  here  is  of  but  little  importance. 

In  the  industries,  however,  where  the  employees  are  exposed  con- 
stantly to  the  dust-laden  air,  its  inhalation  is  seen  to  result  in  certain 


106  DUSTS   IN    AIR. 

important  changes  in  the  tissues  of  the  lungs  and  lymphatics.  These 
changes,  in  many  instances,  are  characteristic  of  the  trade  followed  by 
the  person  affected. 

Most  conspicuous  among  the  tissue  changes  resulting  from  the 
inhalation  of  fine  solid  particles  are  those  seen  in  the  lungs  of  miners, 
or  men  whose  work  necessitates  the  constant  handling  of  coals, 
stokers,  coal  dealers,  etc.  Here  the  coal,  as  such  is  deposited  in  the 
tissues.  In  the  case  of  chimney  sweeps,  the  carbon  is  found  in  a  more 
finely  divided  form,  as  soot.  In  moulders  and  lead-pencil  workers,  it  is 
deposited  as  graphite. 

So  common  is  this  deposit  in  the  lungs  of  miners,  stokers,  etc., 
that  the  condition  is  always  expected.  It  is  known  commonly  as 
•*  miner's  lung,"  anthracosis  being  the  medical  term  for  the  same. 

Siderosis  is  the  term  employed  to  designate  a  condition  of  the 
tissues,  more  particularly  of  the  lungs,  commonly  resulting  from  the 
inhalation  of  iron  or  steel  in  a  finely  divided  form. 

In  the  lungs  of  grinders,  file  makers,  smiths,  potters,  millers,  glass 
polishers,  wool,  cotton  and  wood  workers,  tissue  changes  traceable  to 
the  dust  of  the  trade  followed  by  the  individual,  are  constantly  to  be 
found  after  death. 

Without  going  into  the  details  of  the  different  pathological  processes 
set  up  in  the  lungs  by  the  various  forms  of  solid  matters  which  may  be 
inhaled,  it  will  suffice  to  say  that  in  general  there  appears  primarily  a 
bronchial  catarrh,  followed  by  emphysema.  In  some  cases  interstitial 
changes  in  the  lungs  occur,  rendering  the  tissues  hard,  inelastic,  and 
incapable  of  performing  their  proper  function  (cirrhosis  of  the  lung). 
It  is  plain  that  a  lung  thus  hampered  in  the  performance  of  its  natural 
function  offers  less  resistance  to  the  invasion  of  actually  infective  or 
disease-producing  agents  than  it  otherwise  would. 

Many  observers  believe  in  the  existence  of  a  relation  between 
pneumonia  and  dust  inhalation.  Likewise  pulmonary  phthisis  is 
frequently  attributed  to  this  cause. 

There  appears  to  be  some  difference  in  the  hygienic  significance 
of  the  different  dusts ;  by  some  it  is  claimed  that  pulmonary  consump- 
tion is  less  frequent  in  workmen  who  inhale  the  dust  from  animal  and 
vegetable  matters  than  in  those  inhaling  metallic  and  mineral  particles. 
It  is  a  well-established  fact  that  poisonous  results  are  observed  among 
the  hands  employed  in  lead,  chrome,  mercury,  arsenic,  phosphorus  and 
zinc  works. 

Whether  these  results  are  due  to  inhalation  of  these  substances  in 
finely  divided  form  or  to  the  uncleanly  habits  of  workmen  who  partake 


DUSTS    IN    AIR.  107 

of  their  meals  without  sufficient  attention  to  the  toilet,  is  difficult  to 
say,  as  the  data  at  hand  are  not  of  sufficient  amount  to  justify  positive 
opinion. 

Hesse,  in  his  work,  endeavors  to  establish  a  relation  between  the 
amount  of  dust  present  in  a  given  volume  of  air  and  the  nature  of 
work  from  which  this  dust  is  given  off.  As  a  result,  he  found  per 
cubic  meters  of  air: 

175  Milligrams  of  dust  in  felt  works. 

48  "  "          an  old  mill. 

4  "  "a  new  mill. 

3  "  "          weaving  mill. 

9  "  sculptor's  studio. 

4-25  "  "          paper  mill. 

72-100  "  "          iron  factory. 

14  "  "  coalmine. 

14  " .  "          iron  mine, 

o  "  "          a  dwelling  room. 

These  results  must  be  accepted  as  liable  to  the  greatest  fluctua- 
tion with  varying  conditions.'  Their  principal  value  is  to  illustrate  the 
average  relation  between  the  proportion  of  dust  in  the  air  of  different 
manufacturing  establishments. 

The  pulmonary  consumption  commonly  attributed  to  the  inhala- 
tion of  dust,  is  not  due  to  the  action  of  the  dust  particles  themselves, 
but  to  the  specific  infective  factors  of  the  disease  which  they  carry 
into  the  air  passages. 

It  is  true,  as  said,  that  these  irritating  particles,  even  without  the 
aid  of  living  organisms,  certainly  lessen  the  resisting  powers  of  the 
tissues. by  bringing  about  catarrhal  troubles,  but  of  themselves  they  are 
not  capable  of  establishing  without  aid  the  condition  known  as  con- 
sumption. We  know  now  that  this  disease  depends  for  its  existence 
upon  the  presence  of  a  living  organism  in  the  tissues — the  bacillus 
tuberculosis — we  know,  moreover,  that  this  organism  is  thrown  off  in 
the  expectoration  of  tuberculous  subjects. 

In  nearly  all  workshops,  mills  and  factories  it  is  safe  to  expect  a 
certain  number  of  sufferers  from  this  disease.  Where  no  provision 
against  the  spread  of  the  disease,  in  the  way  of  proper  receptacles  into 
which  these  people  must  expectorate,  are  made,  the  expectoration 
usually  is  upon  the  floor;  it  becomes  dried  and  is  ground  up  with  the 
dust  by  the  feet  of  passers  by  and  enters  the  air  in  the  form  of  finely 
divided  particles,  and  is  inhaled  by  those  engaged  in  the  apartment. 
In  this  way  it  is  fair  to  assume  that  a  certain  amount  of  infection  is 
constantly  taking  place. 


108  VENTILATION  FOR  DRYING  PURPOSES. 

So  long  as  surfaces  are  moist,  it  is  impossible  for  bacteria  to  arise 
from  them  into  the  air.  If,  therefore,  in  the  case  of  workshops  in  which 
a  large  number  of  hands  are  employed,  provision  be  made  by  which 
the  expectoration  shall  conveniently  find  its  way  into  receptacles  con- 
taining water,  there  is  nothing  to  be  feared,  provided  these  receptacles 
are  properly  disinfected  at  regular  intervals. 

In  late  years  many  devices  have  been  suggested  for  diminishing 
the  danger  to  workmen  from  this  source.  Some  of  these  aim  at  less- 
ening the  amount  of  dust  thrown  into  the  air  by  the  employment  of 
moisture  in  the  work,  or  by  causing  grinding,  pulverizing,  etc.,  to  be 
done  in  closed  chambers — others,  where  such  measures  are  not  practi- 
cable, endeavor  to  rid  the  air  of  its  dust  by  ventilation,  while  others 
aim  at  personal  protection  of  the  workmen  by  requiring  them  to  wear 
a  filtering  mask. 

Where  such  measures  are  intelligently  carried  out,  they  result  in 
a  decided  improvement  in  the  well-being  and  comfort  of  the  individuals 
affected  by  them. 

As  is  shown  in  Chapter  VI.,  on  moisture  in  its  relations  to  ventilation, 
we  require  air  to  remove  bodily  heat  as  well  as  to  supply  oxygen — and 
ventilation  is  necessary  to  provide  for  the  evaporation  of  the  water 
from  the  lungs  and  skin,  by  which  a  considerable  part  of  this  cooling 
is  effected.  It  is  also  required  to  remove  moisture  from  damp 
walls,  from  wet  clothing,  and  for  various  purposes  in  the  arts  and  man- 
ufactures in  which  it  is  desirable  to  dry  more  or  less  thoroughly  cer- 
t?in  tissues  or  other  articles.  In  his  very  charming  popular  lectures  on 
the  relations  of  the  air  to  our  clothes  and  houses,  Professor  von  Pet- 
tenkofer  has  shown  the  importance  of  porous  building  materiall  in  the 
walls  of  inhabited  rooms,  and  the  desirability  that  these  pores  should 
be  filled  with  air  and  not  with  water.  In  his  typical  house,  built  with 
100,000  bricks,  he  calculates  that  the  walls  of  the  newly-built  house 
will  contain  about  10,000  gallons  of  water  which  must  be  removed  by 
evaporation  to  make  the  building  healthy.  Assuming  the  average 
temperature  of  the  air  to  be  50°  F.,and  that  its  hygrometric  condition 
is  that  of  75  per  cent,  of  full  saturation,  each  cubic  foot  of  air  is  cap- 
able of  taking  up  about  one  additional  grain  of  water,  or  about  700 
millions  cubic  feet  of  air  are  required  to  dry  the  building  in  question. 

The  process  may  be  hastened  by  raising  the  temperature,  and  this 
is  what  is  often  done  in  new  buildings  to  make  them  sooner  ready  for 
occupancy.  If,  for  instance,  we  heat  air  at  50  degrees,  with  75  per 
cent,  of  saturation,  up  to  70  degrees  it  will  take  up  over  4  grains  of 
water  instead  of  i  to  each  cubic  foot,  while  at  the  same  time  the  move- 


DRYING  ROOMS.  109 

ment  of  the  air  will  be  increased,  and  a  much  larger  quantity  passed 
through  the  house,  so  that  it  may  be  dried  in  one-twentieth  of  the  time 
that  it  would  be  required  if  it  were  left  unheated. 

In  drying  rooms,  or  kilns,  or  cases,  the  object  is  to  remove  the 
superfluous  moisture  by  means  of  heated  air.  For  thin  stuffs  such  as 
muslin  or  paper  the  drying  may  be  effected  by  passing  them  over  heated 
metal  cylinders  freely  exposed  to  the  air — but  as  a  rule  it  is  produced 
by  placing  them  in  a  closed  space  heated  by  metal  pipes,  usually  in  this 
country,  steam  pipes.  A  proper  supply  of  air  is  necessary  for  this  pur- 
pose and  the  quantity  required  depends  on  the  amount  of  moisture  to 
be  removed,  the  amount  of  moisture  in  the  air  when  it  comes  in  con- 
tact with  the  heating  apparatus,  the  amount  of  heat  communicated  to 
it,  and  the  time  which  is  to  be  allowed  for  the  operation.  The  heating 
surfaces  may  be  placed  in  the  space  with  the  articles  to  be  dried,  as  is 
usually  done  in  laundry  drying  rooms,  or  they  may  be  placed  outside 
and  have  the  air  forced  through  them  into  the  drying  room  by  means 
of  a  fan  or  blower,  or  drawn  through  them  by  means  of  an  aspirating 
fan  or  chimney.  For  thick  articles  a  longer  time  and  lower  tempera- 
tures are  desirable  than  for  thin  ones.  Tredgold's  rule  is  that  ''the 
mosi-  economical  rate  of  drying  will  be,  when  the  quantity  of  moisture 
evaporated  in  a  given  time-  is  0.08  times  the  whole  quantity  the  goods 
contain  ;  and  the  time  each  piece  will  have  to  remain  in  the  drying 
room  will  be  about  30  times  the  given  time."  If,  for  instance,  the 
goods  are  to  be  dried  in  30  minutes,  then  the  apparatus  should  be  com- 
petent to  remove  0.08,  or  about  one-twelfth  of  the  total  original  moisture 
in  one  minute.  He  thinks  that  the  heat  most  desirable  to  attain  in  the 
drying  room  is  90°  F.  when  the  dew  point  of  the  external  air  is  40 
degrees.  Under  these  circumstances  he  found  that  nine  grains  of 
water  might  be  evaporated  per  minute  from  a  square  foot  of  surface  of 
cotton  cloth,  which  is  a  cubic  foot  of  water  per  minute  from  2,700 
square  yards  of  cloth,  and  recommends  the  allowance  of  30  cubic  feet 
of  air  per  minute  for  each  square  yard  of  cloth,  or  for  a  piece  of  25 
yards,  750  cubic  feet.  For  this  purpose  he  allows  270  square  feet  of 
radiating  surface  of  steam  pipe  to  effect  the  drying  in  20  minutes,  or 
one-third  of  this  amount  to  effect  the  drying  in  an  hour,  and  the  areas 
of  opening  for  entrance  and  exit  of  air  should  be  about  1%  square  feet. 
Hood  allows  from  15  to  20  square  feet  of  surface  of  hot-water  pipes  to 
100  cubic  feet  of  space  in  common  drying  rooms,  which  in  the  English 
climate  will  heat  the  room  to  about  120  degrees  when  the  room  is 
empty  and  no  change  of  air  is  made  He  states  that  the  temperature 
falls  from  15  to  20  degrees  when  ventilation  is  going  on,  and  that  when 


no 


DRYING    ROOMS. 


the  room  is  filled  with  wet  clothes  the  temperature  falls  to  80  or  90 
degrees.  He  gives  no  data  as  to  air  supply  although  he  rightly  says 
that  ventilation  in  such  cases  is  far  more  important  than  the  degree  of 
heat  maintained  in  the  room.  In  the  drying  rooms  of  ordinary  steam 
laundries,  as  constructed  at  present,  either  no  provision  at  all  is  made 
for  the  entrance  and  exit  of  air  or  it  is  totally  insufficient,  the  result 
being  great  waste  of  heat  and  prolongation  of  the  time  required  to 
effect  desiccation.  The  rule-of-thumb  allowance  of  steam-fitters 
appears  to  be  about  i  square  foot  of  pipe  surface  to  5  cubic  feet  of 
space.  In  his  book  on  steam  heating  Mr.  Baldwin  devotes  a  chapter 
to  drying  by  steam  heat  in  which  he  lays  stress  on  the  fact  that  direct 
radiation  from  surfaces  at  high  temperatures  is  the  most  economical 
method,  but  says  nothing  about  the  quantity  of  air  required.  There  is 
no  doubt  that  the  hotter  the  drying  room  the  less  time  is  required — but 
there  is  also  no  doubt  that  for  most  purposes  a  temperature  above  130°  F. 
is  not  desirable  in  a  drying  room  and  this  will  fall  to  90°  F.,  while 
active  evaporation  is  going  on.  If  insufficient  air  to  carry  off  the  vapor 
be  admitted  much  of  the  effect  of  the  heat  is  lost,  for  when  the  air  is 
thoroughly  saturated  and  the  mixture  of  air  and  vapor  has  been  heated 
up  to  the  capacity  of  the  plant,  no  more  vapor  will  be  absorbed. 

The  following  table  shows  the  number  of  grains  of  water  per 
cubic  foot  which  air  at  various  temperatures  is  capable  of  taking  up 
without  producing  visible  vapor: 


Degrees  Fahr. 

Grains  per  Cubic 
Foot. 

i 
Degrees  Fahr. 

Grains  per  Cubic 
Foot. 

10 

I  .  I 

70 

7-94 

15 

I-3I 

75 

9.24 

2O 

1.56 

80 

10.73 

25 

1.85 

85 

12.43 

30 

2.IQ 

90 

14.38 

35 

2.59 

95 

16.60 

40 

3.06 

IOO 

19.12 

45 

3.6i 

no 

25.5 

50 

4.24 

1  20 

34- 

55 

4-97 

130 

42.5 

60 

5.82 

140 

57. 

65 

6.  Si 

Mr.  Baldwin  remarks  that  an  increase  of  about  25  degrees  in  the 
temperature  of  the  air  doubles  its  capacity  for  taking  up  moisture,  and 
hence,  other  things  being  equal,  an  increase  of  25  degrees  in  the  tem- 
perature of  a  drying  room  will  reduce  the  time  for  drying  one-half, 


DRYING    ROOMS. 


Ill 


Mr.  Box  gives  as  the  result  of  experiments  the  following  figures 
as  regards  the  heat  required  to  evaporate  one  pound  of  water  at  tem- 
peratures below  the  boiling  point  from  open  vessels  exposed  to  air  at 
52°  F.,  and  humidity,  86: 


Temperature  of 
the  Water. 

Number  of  Thermal 
Units  Required  to 
Evaporate  i  Pound 
of  Water. 

Temperature  of 
the  Water. 

Number  of  Thermal 
Units  Required  to 
Evaporate  i  Pound 
of  Water. 

62° 

72° 

82° 
92° 

102° 

2,750 
2,500 
2,280 
2,o8o 
J.QIO 

I42° 
172° 
2O2° 
212° 

1,450 
1,284 
1,203 
1,186 

In  rough  calculations  we  may  assume  that  to  evaporate  a  pound 
of  water  1,500  thermal  units  are  required,  and  that  one  thermal  unit 
will  heat  50  cubic  feet  of  air  i°  F.,  hence  to  evaporate  100  pounds  of 
water  by  air  heated  from  60  to  130  would  require  150,000  x  50  -f- 
70  =  107,143  cubic  feet  of  air  to  convey  the  heat.  If  this  air  is 
capable  of  taking  up  7  grains  of  water  per  cubic  foot  from  the  moist 
surfaces,  it  would  require  100,000  cubic  feet  of  air  to  take  up  100 
pounds  of  water,  and  it  would  be  better  to  allow  1,500  cubic  feet  of  air 
to  each  pound  of  water  to  be  removed,  to  which  air  at  least  1,500 
thermal  units  of  heat  must  be  communicated. 

In  this  connection  the  following  data  with  regard  to  the  drying 
room  of  the  laundry  of  the  Johns  Hopkins  Hospital  in  Baltimore, 
for  which  data  I  am  indebted  to  the  Superintendent,  Dr.  Hurd,  will 
be  of  interest: 

The  dry  room  is  9  feet  6  inches  wide  by  22  feet  long  by  9  feet 
high,  and  contains  1,881  cubic  feet.  It  is  heated  with  27  coils  of  i- 
inch  pipe,  9  feet  long  by  4  pipes  high,  which  gives  324  square  feet  of 
radiating  surface  There  are  25  racks  9  by  9  feet,  2  inches  thick 
when  filled  with  clothes,  which  gives  337  cubic  feet.  The  air  is  sup- 
plied through  50  i  %• inch  holes  (two  near  the  bottom  of  each  rack), 
each  of  which  supplies  about  80  feet  per  minute.  The  exit  for  the  air 
is  through  a  12  by  14  register  into  the  vent  shaft.  The  temperature  of 
the  air  coming  through  this  register  is  42°  C.  (107.6°  F.)  when  the 
dryer  is  filled  with  clothes. 

With  55  pounds  of  steam  pressure  at  the  boiler,  the  temperature  of 
the  room  when  empty  is  72°  C.  (161.6°  F.)  ;  when  filled  with  wet 
clothes  it  falls  to  56°  C.  (132.8°  F.) 


112 


DRYING    ROOMS. 


It  takes  from  30  to '40  minutes  to  dry  unstarched  clothes,  and 
about  ten  minutes  longer  for  starched  ones. 

With  45  pounds  steam  pressure  at  boiler,  and  a  temperature  of 
70°  C.  in  the  empty  dr}rers,  10  wet  sheets  weighing  22^  pounds  were 
placed  on  the  racks.  In  20  minutes  the  sheets  were  dry,  weighing  15 
pounds,  and  the  temperature  in  the  dryers  was  65°  C.  After  these 
sheets  were  passed  through  the  mangle  they  weighed  14%  pounds. 

One  flannel  skirt,  containing  two  square  yards,  on  coming  from 
the  wringer  weighs  2  Ibs.  2  oz.;  on  coming  from  the  dryer  i^  pounds. 

One  spread,  containing  5^i  square  yards,  coming  from  the 
wringer  weighs  5  pounds  ;  from  dryer,  3^  pounds  ;  from  mangle,  2% 
pounds. 

One  bleached  sheet,  containing  5^  square  yards,  coming  from 
wringer,  weighs  3  pounds  ;  from  dryer,  i^  pounds  ;  from  mangle,  i^ 
pounds. 

One  blanket,  containing  3^2  square  yards,  coming  from  wringer, 
weighs  4  pounds  ;  from  dryer,  z%  pounds. 

The  following  data  are  furnished  from  the  laundry  of  the  Hos- 
pital of  the  University  of  Pennsylvania  : 


Wet. 

Dry 

6  blankets                

17 

12 
12 

6 

2 

I 

pot 

C 

ends,    YZ   oun 
13 
13* 

8/2 
12 

14* 

:es. 

12  pOU 

8 
8 
5 

2 
I 

nds,  12^  ounces. 
13*         " 

••$   :: 

i*      " 

8 

6  spreads.           

6  sheets  

6  shirts  

6  towels  ...       

In  this  laundry,  the  steam  pipes  form  a  flat  grating  near  the  floor 
and  the  supply  of  air  is  very  small  except  by  leakage.  In  one  trial,  on 
a  clear  day,  external  temperature,  60°  F.,  72^  pounds  of  water  were 
evaporated  in  90  minutes,  the  temperature  before  putting  in  the  wet 
clothes  being  144  degrees  ;  immediately  after  filling,  90  degrees  ;  in  five 
minutes,  99  degrees;  in  20  minutes,  114  degrees;  in  40  minutes,  120 
degrees;  in  60  minutes,  125  degrees,  and  in  90  minutes,  132  degrees. 

In  another  trial,  on  a  cold,  raw  day,  with  rain,  24  sheets,  1 8  blank- 
ets, 24  spreads,  45  pillow  cases,  24  night  shirts  and  72  towels,  weighing, 
while  wet,  247^  pounds,  were  placed  in  the  drying  room,  which  was 
then  at  a  temperature  of  146°  F.  In  five  minutes  the  temperature  was 
100  degrees;  in  20  minutes,  115  degrees  ;  in  35  minutes,  120  degrees, 
and  in  90  minutes,  132  degrees.  The  clothes  were  then  taken  out  and 


DRYING    ROOMS.  113 

found  to  weigh  157^  pounds,  showing  that  89^  pounds  of  water  had 
been  evaporated  in  90  minutes.  In  each  case  trie  steam  was  at  70 
pounds  pressure.  With  a  proper  arrangement  of  the  radiating  surface 
and  sufficient  air  supply,  this  amount  of  work  should  have  been  done  in 
less  than  half  the  time  actually  occupied. 

The  following  data  in  regard  to  drying  rooms  were  kindly 
furnished  by  Messrs.  Bartlett,  Hayward  &  Co.,  of  Baltimore.  "  The 
drying  kiln  for  lumber  of  A.  H.  Andrews  &  Co.,  of  Chicago,  has  a 
capacity  of  24,000  feet  pine  boards  ;  the  size  of  the  room  is  1 7'x5  2'xi 2' 
in  clear  heights  ;  the  heating  surface  is  8,000  feet  i-inch  pipe,  the 
steam  pressure  80  pounds  per  square  inch  ;  there  are  eight  vents 
b"x8* ;  the  time  required  for  drying  is  five  days.  The  kiln  of  R.  B. 
Andrews,  of  Baltimore,  brick  dryers,  has  a  capacity  of  25,000  bricks; 
the  size  of  the  room  is  is'xno'xS',  the  heating  surface  11,000  feet 
of  i-inch  pipe;  the  time  required  to  dry  the  bricks  ready  for  burning  is 
24  to  72  hours,  according  to  kind  of  clay.  The  heat  has  to  be  gradu- 
ated to  suit  the  quality  of  the  clay  ;  generally  the  temperature  is  quite 
low  at  first  until  the  bricks  are  heated  through,  then  the  temperature  is 
gradually  raised  before  any  air  is  admitted." 

It  becomes  at  times  very  necessary  to  entirely  change  the  air  in  an 
enclosed  space  in  order  to  prevent  the  formation,  or  the  removal  if 
formed,  of  an  explosive  mixture  of  gases,  or  of  a  collection  of  gas  not 
explosive,  but  dangerous  to  life.  This  may  occur,  for  example,  in  a 
petroleum  tank  steamer  when  the  oil  has  been  pumped  out.  A  con- 
siderable quantity  of  gas  from  the  residual  fluid  accumulates,  and  by 
mixture  with  the  atmospheric  air  by  the  process  of  diffusion  a  mixture 
is  formed  which  the  introduction  of  a  light  will  cause  to  explode  with 
great  violence.  This  accident  has  occurred  several  times.  As  examples 
of  the  accumulation  of  carbonic  acid  to  such  an  extent  as  to  make 
the  air  irrespirable,  may  be  taken  the  case  of  large  brewing  vats  when 
emptied  of  their  liquid  contents — or  of  certain  deep  cesspools,  or  of 
wells  where  the  deep-ground  air  contains  a  high  proportion  of  the  gas. 

In  the  case  of  explosive  mixtures,  what  is  required  is  me- 
chanical ventilation  by  means  of  a  fan  so  arranged  with  a  movable 
duct,  that  the  whole  of  the  room  or  tank  can  be  thoroughly  flushed 
out.  In  the  case  of  foul  or  irrespirable  gases  not  explosive, 
mechanical  means  may  also  be  used  in  the  form  of  a  sort  of  extem- 
porized pump,  in  which  an  umbrella  may  be  made  the  piston,  but  in 
these  cases  it  will  often  be  found  more  convenient  to  use  heat  by 
burning  a  bundle  of  straw  or  shavings,  to  secure  an  upward  current. 


CHAPTER   VI. 

ON  MOISTURE  IN  AIR,  AND  ITS  RELATIONS  TO  VENTILATION. 


relations  of  atmospheric  moisture  to  health  and  comfort  are 
interesting  and  important  in  connection  with  arrangements  for 
ventilation  and  heating.  These  relations  depend  in  part  on  the  influ- 
'ence  which  the  proportion  of  humidity  in  the  surrounding  air  has  on 
the  evaporation  of  moisture  from  the  air  passages  and  external  surface 
of  the  human  body,  and  in  part  on  the  peculiar  relations  which  exist 
between  the  exhaled  watery  vapor  and  the  volatile  organic  matter 
escaping  from  the  lungs. 

A  healthy  man  of  average  size  in  the  course  of  24  hours  trans- 
forms into  actual  energy  from  the  potential  energy  which  has  been 
supplied  to  his  tissues  in  the  form  of  food,  an  amount  equal  to  about 
3,400  foot-tons,  of  which  about  300  foot-tons  is  the  amount  of  mus- 
cular force  exerted  in  a  good  day's  work,  260  foot-tons  is  the  amount 
of  visceral  work  done  by  the  heart,  the  muscles  of  respiration,  the 
glands,  etc.,  and  2,840  foot-tons  appears  in  the  form  of  heat.  The 
visceral  work  also  appears  ultimately  as  heat,  just  as  the  work  going  on 
in  a  watch  that  is  running  raises  its  temperature. 

Another  way  of  stating  it  is  that  the  heat  income  of  the  body  due 
mainly  to  oxidation  of  hydro-carbons  amounts  to  from  2  to  2^  millions 
of  calories  daily,  depending  upon  age,  sex,  amount  of  exercise,  diet, 
etc.  All  this  energy  is  set  free  as  mechanical  labor  and  as  heat. 

Of  this  heat,  192,060  calories  are  expended  in  evaporating  330 
grammes  of  water  from  the  lungs,  and  384,120  calories  in  evaporating 
660  grammes  of  water  from  the  skin  —  that  is,  about  23  per  cent,  of  the 
heat  is  used  in  this  way,  while  about  72  per  cent,  is  radiated  and  con- 
ducted from  the  skin,  and  the  remainder  is  lost  in  heating  the  air 
inspired,  and  the  excretions  from  the  bowels  and  kidneys.* 

If  this  heat  is  not  gotten  rid  of  promptly  and  regularly,  discom- 
fort is  soon  produced,  and  it  will  be  seen  from  the  above  figures  that 
the  greater  part  of  it  goes  through  conduction  and  evaporation.  The 

*  Landois'  riuman  Physiology.     London,  1888,  p.  332. 


MOISTURE    IN    THE    AIR.  115 

rapidity  with  which  evaporation  goes  on,  depends  on  the  capacity  for 
taking  up  moisture  possessed  by  the  surrounding  air,  and  this  depends 
upon  its  temperature  and  the  amount  of  moisture  which  it  already 
contains. 

Air  that  is  loaded  with  moisture  transmits,  in  each  unit  of  time,  much 
more  heat  than  air  which  is  dry.  Hence,  when  air  at  a  high  tempera- 
ture is  saturated  with  moisture,  it  communicates  heat  to  the  body,  pro- 
ducing an  oppressive  sensation,  but  when  the  temperature  of  the 
saturated  air  is  lower  than  the  temperature  of  the  body,  the  transfer  of 
heat  goes  on  rapidly  from  the  body  to  the  air  and  produces  a  sensation 
of  cold.  A  low  temperature  with  a  dry  atmosphere  is,  therefore,  more 
comfortable  than  a  higher  temperature  when  the  air  is  loaded  with 
moisture. 

At  and  below  the  freezing  point  air  contains  so  little  vapor  that 
it  may  be  called  dry.  Air  completely  saturated  with  moisture  at  tem- 
peratures of  from  35  °F.  to  45  °F.  removes  heat  rapidly  from  the  surface 
of  the  body,  not  so  much  by  evaporation  as  by  conduction,  and  is  felt 
to  be  very  chilly. 

At  temperatures  of  between  55°F.  and  65  °F.  moist  air  is  felt  as 
very  comfortable,  neither  too  hot  nor  too  cold,  while  above  7o°F.  a 
saturated  atmosphere  feels  sultry  and  oppressive,  and  if  the  tempera- 
ture be  above  9o°F.  it  becomes  exhausting.  On  the  other  hand,  dry 
air  at  temperatures  of  from  32 °F.  to  8o°F.  is  not  specially  uncomfort- 
able if  proper  clothing  be  worn,  and  is  certainly  not  injurious  to  health. 

At  Fort  Yuma,  California,  which  used  to  be  famous  as  the  hottest 
military  post  in  the  United  States,  during  the  months  of  April,  May 
and  June,  when  no  rain  falls,  with  the  thermometer  at  ioo°F.,  or  even 
at  ii2Q  F.,  the  skin  becomes  dry  and  hard,  the  hair  crisp,  furni- 
ture falls  to  pieces,  newspapers  must  be  handled  carefully  or  they  will 
break,  and  a  No.  2  lead  pencil  leaves  no  more  trace  on  paper  than  a 
piece  of  anthracite — yet  under  these  conditions,  lasting  for  weeks,  there 
is  no  special  increase  in  sickness. 

Dr.  Wyman  states  that  the  Harmattan,  a  wind  which  blows  from 
the  scorching  sands  of  Africa,  drying  the  branches  of  trees,  cracking 
doors  and  furniture,  and  drying  the  eyes,  lips  and  throat,  so  that  they 
are  painful,  is  not  an  unhealthy  wind  ;  on  the  contrary,  its  first  breath 
cures  intermittent  fevers,  and  malarial  affections  disappear  as  if  by 
enchantment.  A  dry  air,  with  a  uniform  temperature,  makes  a  healthy 
climate,  as  in  New  Mexico. 

In  general,  dry  climates,  especially  where  the  temperature  is  equa- 
ble, are  considered  to  be  the  most  healthy.  English  authorities  on 


110  MOISTURE    IN    THE    AIR. 

heating  usually  assume  that  the  proper  temperature  of  inhabited  rooms 
should  be  about  6zp  F.,  while  the  American  standard  is  70°  F.,  and, 
although  these  differences  are  partly  due  to  habit,  they  are  also,  to  a 
very  considerable  extent,  due  to  differences  in  climate,  and  especially 
to  the  differences  in  the  amount  of  moisture  in  the  air. 

If  the  air  be  at  32°  F.,  and  dry,  a  person  loses  by  respiration  1,172 
thermal  units,  and  if  the  air  be  at  86°  F.,  and  quite  dry,  he  loses  1,096 
thermal  units — the  difference  being  only  76.  But  if  the  air  be  satu- 
rated with  moisture  at  these  two  temperatures,  he  will  lose  at  32  degrees 
1,062,  and  at  86  degrees,  420  thermal  units — a  difference  of  640 — which 
will  make  him  feel  very  hot  and  uncomfortable.  We  need  air  for 
cooling  almost  as  much  as  we  do  for  the  oxygen  it  contains — and  the 
power  which  it  has  to  convey  away  our  surplus  heat,  depends  greatly 
on  its  moisture  (Pettenkofer). 

When  we  turn  to  artificial  climates,  we  find  that  in  our  houses  in 
winter,  with  the  external  air  at  32°  F.,  the  percentage  of  moisture  is 
often  between  30  and  40  without  producing  any  discomfort. 

There  can  be  no  better  illustration  of  this  than  the  results  obtained 
by  Dr  Cowles  in  the  Boston  City  Hospital,  and  published  by  him  in 
the  report  of  the  Massachusetts  State  Board  of  Health  for  1879. 

He  says  :  "  I  believe  that  no  discomfort  has  been  felt  or  ill-effects 
produced  from  the  low  relative  humidity,  even  on  the  occasions  when 
there  was  only  15  to  21  per  cent,  of  saturation.  According  to  Dr.  De 
Chaumont,  so  great  dryness  is  inconsistent  with  a  healthful  condition 
of  the  atmosphere.  Certainly,  in  this  ward  there  is  uniformly  observed 
a  remarkable  absence  of  complaint  of  any  kind  that  can  be  ascribed  to 
the  condition  of  the  air,  and  a  peculiar  feeling  of  its  freshness  and 
purity  is  frequently  spoken  of  by  those  who  enter  the  room." 

It  is  evident,  therefore,  that  it  is  not  necessary  to  supply  moisture 
enough  to  heated  air  to  bring  the  percentage  up  to  70.  It  is  also  to 
be  noted  that  it  will  take  about  the  same  amount  of  fuel,  or,  in  other 
words,  will  cost  as  much  to  furnish  this  percentage  of  moisture  to  air 
heated  from  30°  F.  to  70°  F.,  as  it  does  to  heat  the  air  Moreover,  in 
a  room  properly  ventilated  under  such  circumstances,  it  would  be 
practically  almost  impossible  to  maintain  such  a  percentage  of  moisture, 
owing  to  the  great  rapidity  with  which  the  vapor  of  water  diffuses  in 
such  dry  air  and  the  condensation  which  would  occur  on  windows  and 
thin  outer  walls.  This  whole  subject  has  been  well  discussed  by  Mr. 
Robert  Briggs,  in  a  paper  entitled,  "  On  the  Relation  of  Moisture  in 
Air  to  Health  and  Comfort,"  published  in  the  Journal  of  the  Franklin 
Institute  tor  1878,  and  to  this  I  would  refer  for  further  details. 


MOISTURE    IN    THE    AIR.  117 

In  a  paper  on  the  "Theory  of  Ventilation,"  by  Dr.  De  Chaumont, 
published  in  the  Proceedings,  of  the  Royal  Society  of  London,  Volume 
XXV.,  1876-77,  page  i « ,  he  concludes,  from  the  result  of  his  investiga- 
tion, that  "an  increase  of  i  per  cent,  of  humidity  has  as  much  influ- 
ence on  the  condition  of  air  space  (as  judged  of  by  the  sense  of  smell) 
as  a  rise  of  4.18  degrees  of  temperature  in  Fahrenheit's  scale,  equal  to 
2.32°  C.,  or  1.86°  Reaumur. 

"This  may  be  taken  as  a  proof  of  the  powerful  influence  exercised 
by  a  damp  atmosphere,  corroborating  the  conclusions  arrived  at  by 
ordinary  experience ;  and  it  follows  that  as  much  care  ought  to  be 
taken  to  ensure  proper  hygrometric  conditions  as  to  maintain  a  suffi- 
ciently high  temperature.  This  is  especially  the  case  in  the  wards  or 
chambers  of  the  sick,  in  which  regular  observations  with  the  wet-and- 
dry-bulb  thermometers  ought  to  be  made  ;  these  would  probably  give 
a  valuable  indication  of  the  ventilation,  either  along  with  or  in  the 
absence  of  other  more  detailed  investigations.  Thus  a  room  at  the 
temperature  of  60°  F.  and  with  88  per  cent,  of  humidity  contains  5.1 
grains  of  vapor  per  cubic  foot;  suppose  the  external  air  to  be  at  50°  F., 
with  the  same  humidity,  88  per  cent ;  this  would  give  3.6  grains  of 
vapor  per  cubic  foot;  to  reduce  the  humidity  in  the  room  to  73  per 
cent,,  or  4.2  grains  per  cubic  foot,  we  must  add  the  following  amount 
of  external  air  : 

5.1X4.2 
4.2X3.6- 

or  once  and  a  half  the  volume  of  air  in  the  room.  If  the  inmates  have 
each  1,000  cubic  feet  of  space,  it  follows  that  either  their  supply  of 
fresh  air  is  short  by  1,500  cubic  feet  per  head  per  hour,  or  else  that 
there  are  sources  of  excessive  humidity  within  the  air  space  which 
demand  immediate  removal." 

The  effects  produced  in  air  by  artificial  heat,  and  which  by  some 
are  supposed  to  be  connected  with  insufficient  moisture,  are  impc-rtant, 
and  merit  more  study  than  they  have  yet  received. 

Dr.  Ure  describes  the  effects  of  the  use  of  highly-heated  cockle 
stoves  to  be  tension  or  fullness  of  the  head,  flushings  of  the  coun- 
tenance, frequent  confusion  of  ideas,  coldness  of  the  extremities,  and 
feeble  pulse.  Hood  confirms  this,  and  states  that  he  examined  a 
school  heated  in  the  same  manner,  and  found  it  be  so  pernicious  to  the 
health  of  the  children  that  they  occasionally  dropped  off  their  seats  in 
fainting  fits.  He  goes  on  to  say  that  "these  pernicious  effects, 
although  generally  in  a  somewhat  less  degree,  always  result  from  the 
use  of  intensely  heated  metallic  surfaces.  They  are,  however,  much 


Il8  MOISTURE  IN  THE  AIR. 

modified  if  the  air  is  tempered  by  the  evaporation  of  water.  In 
Russia  and  Sweden,  and  other  places  where  close  stoves  are 
used,  an  earthen  vessel  of  water  is  always  placed  on  the  stove 
for  this  purpose,  and  greatly  mitigates  the  oppressive  effects 
which  would  otherwise  be  experienced.  The  desiccating  power  of  the 
air  increases  with  the  temperature  to  a  very  great  extent.  Air  at  32 
degrees  contains,  when  saturated  with  moisture,  T^T*  of  its  weight  of  water ; 
at  59  degrees  it  contains  irb  ;  at  86  degrees  it  contains  ?V,  its  capacity  for 
moisture  being  doubled  by  each  increase  of  27°  F. 

Of  the  reality  of  the  effects  referred  to  by  Dr.  Ure  and  Mr.  Hood, 
as  resulting,  in  some  cases,  at  all  events,  from  heating  air  intended  for 
respiration  to  a  high  temperature,  there  is  no  doubt,  but  that  these 
effects  are  especially  connected  with  the  dryness  of  the  air  is  not 
probable. 

English  writers  usually  state  that,  in  order  to  secure  health  and 
comfort,  the  relative  saturation  with  moisture  of  air  to  be  respired 
should  be  from  65  to  75  per  cent.  Mr.  Hood  says  that,  u  in  rooms 
artificially  heated,  the  most  healthy  state  of  the  atmosphere  will  be 
obtained  when  the  dew  point  of  the  air  is  not  less  than  10°  nor  more 
than  20°  F.  lower  than  the  temperature  of  the  room."  Dr.  De 
Chaumont  states  that  for  England  the  difference  between  the  wet  and 
dry  bulb  thermometers"  ought  not  to  be  less  than  4  degrees  nor  more 
than  5  degrees,  and  that  the  percentage  of  humidity  should  not  exceed 
.75,  while  Hood  declares  that  we  should  endeavor  to  maintain  in 
artificially  heated  rooms  82  per  cent,  of  moisture.  There  is  little  doubt 
that  De  Chaumont  is  more  nearly  correct  than  Hood,  so  far  as  the 
English  climate  is  concerned,  but  none  of  these  figures  will  apply 
in  the  United  States,  as  has  been  shown  above. 

But  if  it  is  not  the  dryness  of  the  air  which  causes  the  disagree- 
able sensations  whose  frequency  in  furnace  and  steam-heated  rooms 
no  one  can  deny,  what  is  it? 

The  answer  is,  that  it  is  no  single  cause,  but  a  combination  of  a 
number  of  causes.  The  first  and  most  important  is  the  want  of 
sufficient  fresh  air  to  insure  satisfactory  ventilation.  The  amount  of 
air  required  for  this  purpose,  if  admitted  after  passing  through  the 
heating  chamber  of  an  ordinary  furnace,  would  soon  make  the  room 
insufferably  hot,  for  on  a  cold  day  its  temperature  from  the  common 
forms  of  apparatus  will  average  180°  F.  To  prevent  this,  the 
register  is  usually  partially  or  entirely  closed  as  soon  as  the  room 
becomes  unpleasantly  warm,  and  the  fresh  air  is  thus  shut  off  as  well 
as  the  heat. 


FURNACE    AIR.  119 

The  second  cause  is  the  contamination  of  the  fresh  heated  air  by 
gases  from  the  furnace,  and  especially  by  carbonic  oxide.  This  will  be 
found  to  be  the  chief  trouble  in  those  cases  where  a  dull,  persistent 
headache,  with  the  feeling  as  if  an  iron  band  were  bound  around  the 
head,  is  produced,  or  in  such  cases  as  those  mentioned  by  Ure  and 
Hood. 

From  hot-air  furnaces  these  gases  pass  mainly  at  the  joints,  and 
the  more  joints  a  furnace  has  the  worse  it  is  in  this  respect. 

A  very  common  cause  of  impurity  in  air  heated  either  directly  by 
furnaces  or  indirectly  by  steam  or  hot  water,  when  the  furnace  is  in 
the  cellar,  is  leakage  from  the  cellar  into  the  cold-air  flues  or  chambers. 
Brick  piers,  inclosing  coils  or  radiators,  are  quite  pervious  to  air,  and 
the  pipes  or  box  flues  used  to  bring  fresh  air  to  the  heating  surfaces 
leak  very  decidedly  in  the  majority  of  cases. 

A  very  common  method  used  by  servants  for  diminishing  heat 
is  to  open  the  furnace  door,  and  at  the  same  time  to  obstruct  the 
draught  below.  This  gives  r,ise  to  large  volumes  of  carbonic  oxide, 
some  of  which  will  almost  assuredly  escape  into  the  cellar  and  it  re- 
quires the  presence  of  but  a  very  small  percentage  of  this  gas  to  pro- 
duce bad  results. 

The  last  cause  of  discomfort  which  need  be  mentioned  here,  is 
overheating  in  rooms  which  are  occupied  by  a  number  of  persons.  In 
personal  inspections  in  public  offices,  I  have  usually  found  the  tempera- 
ture to  be  between  75°  and  80°  F.,  to  suit  the  sensations  of  the  older 
and  feeble  clerks. 

On  a  cold  day  the  windows  of  an  uninhabited  room  exert  a  tem- 
porary purifying  influence  on  the  air  of  the  room  by  condensing  the 
moisture,  and  with  it  a  considerable  quantity  of  organic  matter,  and 
the  same  effect  is  produced  by  the  snow  houses  of  the  Esquimaux. 


CHAPTER  VII. 

QUANTITY    OF    AIR    REQUIRED    FOR    VENTILATION. 

THE  dimensions  of  flues  and  registers,  the  quantity  of  heating  sur- 
face, and  the  amount  of  motive  power  required  for  the  ventilation 
of  a  building  or  locality,  depend  upon  the  amount  of  fresh  air  that  is 
to  be  supplied  in  a  given  time.  It  is  in  the  determination  of  this 
amount  that  the  young  architect  or  engineer  is  likely  to  find  his  chief 
difficulties,  owing  to  the  great  divergence  of  opinion  among  the 
authorities  to  whom  he  will  probably  refer  for  guidance. 

As  has  been  shown  in  the  chapter  on  the  history  of  ventilation, 
the  figures  for  quantity  of  air  per  person  per  hour  in  assembly  halls  and 
hospitals  were  constantly  increased  by  successive  ventilators,  but  upon 
no  definite  principle  or  rule,  until  the  introduction  of  the  chemical 
method  of  testing  the  results.  When  it  was  found  that  the  proportion 
of  carbonic  acid  present  might  be,  with  certain  precautions,  accepted 
as  a  measure  of  the  amount  of  offensive  or  dangerous  impurity  in  the 
air,  the  next  question  was,  how  great  a  proportion  of  carbonic  impurity, 
that  is,  of  carbonic  acid  added  to  the  air  of  a  room  by  the  respirations 
and  exhalations  of  its  inmates,  is  to  be  considered  as  permissible,  or 
not  undesirable  or,  in  other  words,  as  corresponding  to  what  may  be 
properly  called  good,  or  fair,  or  bad  ventilation  ? 

'  This  question  cannot  be  answered  properly  by  considering  the 
effects  upon  health  produced  by  exposures  to  foul  air  for  a  few 
hours  only,  since  these  are  rarely  perceptible  unless  the  impurity  is 
very  great. 

It  requires  the  observation  of  the  effects  on  the  health  and 
life  of  a  number  of  men  exposed  to  such  air  for  a  series  of  months 
or  of  years,  to  demonstrate  the  slow  but  certain  production  of  throat 
and  lung  troubles,  the  loss  of  energy  and  vitality  and  the  shortening  of 
life,  which  are  thus  produced.  These  observations  have  been  made  on 
soldiers  occupying  ill-ventilated  barracks,  and  on  operatives  working 
in  close  work  rooms,  and  comparison  of  the  results  has  shown  that, 
when  in  any  room  occupied  by  human  beings  there  is  a  definite,  un- 
pleasant animal  or  musty  odor,  perceived  by  a  person  whose  sense  of 


QUANTITY    OF    AIR    REQUIRED.  121 

smell  is  of  the  usual  acuteness  and  who  enters  the  room  from  the  fresh 
outer  air,  then  continued  breathing  of  the  air  producing  such  odor 
will  be  injurious  to  health. 

The  sense  of  smell  is  soon  blunted,  and  after  one  has  remained  for 
10  or  15  minutes  in  an  ill- ventilated  school  or  theater,  he  will  probably 
not  perceive  any  specially  unpleasant  odor,  although  he  may  feel  hot 
and  uncomfortable,  and  possibly  have  a  slight  headache  as  the  result. 

Careful  observations  have  been  made  upon  the  relations  between 
such  odors  as  are  referred  to  above  and  the  proportions  of  carbonic 
acid  present,  and  the  results  which  are  now  generally  accepted  as 
authoritative,  having  been  confirmed  by  subsequent  observers,  are 
those  reported  by  Dr.  De  Chaumont.  From  a  large  number  of  experi- 
ments he  obtained  a  series  of  data  which  he  divides  into  five  classes. 
In  the  first  class  the  observer  found  no  sensible  difference  in  odor 
between  the  air  of  the  room  and  that  of  the  external  air.  In  those  in 
which  the  air  is  called  "  fresh  "  the  temperature  was  about  63°  F.,  the 
vapor  and  humidity  4.7  gr.  per  cubic  foot,  and  the  carbonic  impurity 
due  to  respiration  was  1.943  in  10,000  volumes.  This  shows  satis- 
factory ventilation. 

2.  When  the  organic   matter  begins   to  be   appreciated   by  the 
senses,  and  the  air  is  said  to  be  ''rather  close,"  the  vapor  and  humidity 
averaged  7.6,  and  the  carbonic  respiratory  impurity  was  4. 132  per  10,000. 

3.  When  the  smell  begins  to  be  decidedly  disagreeable,  and  the  air 
is  called  "close,"  the  vapor  and  humidity  averaged  4.9,  and  the  carbonic 
impurity  was  from  6.5  to  TO. 

4.  When  the  organic  matter  is  decidedly  offensive  and  oppressive 
the  air  is  called  "very  close,"  and  the  carbonic  impurity  is  about  12. 
Above  this  the  sense  of  smell  is  no  longer  capable  of  perceiving  marked 
differences.1 

His  conclusion  from  these  results  is  that  to  insure  the  absence  of 
the  odor  of  organic  matter  in  an  inhabited  apartment,  or  what  he  terms 
"  good  ventilation,"  the  carbonic  impurity  due  to  respiration  should 
nut  exceed  2  parts  in  10,000,  and  this  is  the  standard  accepted  by  Dr. 
Parkes  and  by  most  recent  English  writers  on  this  subject. 

While  this  relation  between  the  amount  of  carbonic  acid  due  to 
respiration,  and  the  amount  of  organic  matter  contained  in  the  air  of 
an  inhabited  room,  and  between  the  latter  and  the  odor  produced  will 
be  found  to  exist  as  a  general  rule,  it  varies  greatly  under  certain  cir- 
cumstances. 

1  Proc.  Roy.  Soc.,  London,  1875,  p.  187  ;  ibid.,  Vol.  XXV.,  1876-7,  p.  116. 


122  QUANTITY    OF    AIR    REQUIRED. 

The  smell  of  organic  matter  may  not  be  perceptible  when  the  car- 
bonic impurity  due  to  respiration  is  as  high  as  5  parts  in  10,000,  and  it 
may  be  very  decided  when  the  carbonic  impurity  does  not  exceed  3  per 
10,000.  It  depends  in  part  on  the  temperature  and  the  amount  of 
moisture  present — in  part  on  the  amount  of  diffusion  going  on — for 
the  organic  matters  do  not  diffuse  as  readily  as  the  CO2.  Absence  of 
odor  does  not  prove  the  absence  of  dangerous  particulate  impurities  in 
the  air,  for,  although  typhus,  smallpox  and  yellow  fever  cases  produce 
distinct  odors,  yet  there  are  many  of  the  specific  diseases  which  give 
no  warning  of  this  kind.  There  does  not  seem  to  be  any  relation  be- 
tween the  number  of  micro-organisms  and  the  proportion  of  carbonic 
acid  in  the  air. 

The  number  of  observations  reported  by  thoroughly  competent 
and  reliable  observers  as  to  the  relations  between  respiratory  carbonic 
impurity,  organic  matter,  humidity  and  temperature  are  at  present 
much  too  few  to  permit  of  drawing  any  conclusions  of  much  practical 
value  as  regards  ventilation,  and  it  is  very  desirable  that  further  inves- 
tigations should  be  made  on  this  point. 

It  must  also  be  borne  in  mind  that  in  adopting  any  standard  of 
purity  of  the  air  as  expressed  by  the  proportion  of  carbonic  acid  found 
to  be  present,  it  is  assumed  that  the  amount  of  CO2  found  in  excess  of 
that  which  exists  in  the  external  air  is  entirely  due  to  respiration,  and 
on  the  other  hand  that  all  the  excess  of  CO2,  due  to  respiration,  is 
present  in  a  form  to  be  determined  by  the  chemical  test.  If,  for  ex- 
ample, one  or  more  lights  are  burning  in  the  room,  we  shall  find  an 
excess  of  carbonic  acid  in  the  air  of  that  room  which  has  no  relation  to 
the  organic  impurities  present.  On  the  other  hand,  if  ammonia  be 
present  in  the  air,  as  in  stables  near  the  floor,  it  combines  with  a  part 
of  the  carbonic  acid,  and,  although  the  resulting  ammonium  carbonate 
is  decomposed  by  the  baryta  solution  in  making  the  chemical  test,  yet 
the  ammonia  then  set  free  in  the  solution  requires  a  certain  amount  of 
the  standard  oxalic  acid  solution  to  neutralize  it,  and  hence  the  pro- 
portion of  carbonic  acid  present  appears  to  be  smaller  than  it  really  is. 

Having  fixed  upon  a  standard  of  permissible  carbonic  impurity 
due  to  respiration,  it  is  easy  to  calculate  the  amount  of  air  required  to 
dilute  the  air  expired  by  an  individual  for  a  given  time,  so  that  the 
CO2  contained  in  the  mixture  shall  not  exceed  this  standard.  The 
amount  of  carbonic  acid,  over  and  above  that  inspired,  which  is  exhaled 
by  a  person  during  an  hour,  varies  with  his  weight,  and  the  state  of 
activity  of  the  different  organs  of  his  body.  Men  exhale  more  than 
women,  adults  more  than  children,  those  who  are  awake  more  than  those 


QUANTITY    OF    AIR    REQUIRED.  123 

who  are  asleep.  According  to  Landois  and  Stirling,*  males  from  the 
eighth  year  onward  to  old  age,  give  off  about  one-third  more  CO2  than 
females.  In  old  age  the  amount  of  CO2  exhaled  diminishes.  Thus, 
in  24  hours  the  number  of  grammes  of  CO2  excreted  is,  at  the  age  of 
15,  766  ;  at  the  age  of  24,  1,074  ;  at  the  age  of  50,  889  ;  and  at 
70,  810. 

For  an  adult  male,  Pettenkofer  found  that  for  each  pound  weight 
of  the  body  there  was  excreted,  in  repose,  0.00424  ;  in  general  exer- 
cise, 0.00591  ;  and  in  hard  work  0.01227  cubic  feet  of  carbonic  acid 
per  hour.  Children  excrete  nearly  twice  as  much  CO2  per  pound  of 
body  weight.  During  sleep  the  amount  of  CO2  given  off  is  diminished 
by  nearly  one-fourth.  In  a  person  affected  with  fever  the  amount  is 
markedly  increased.  A  fair  average  of  the  amount  of  CO2  excreted 
per  hour  is,  for  adult  males,  from  0.6  to  0.7  cubic  foot  per  hour,  and 
for  females,  0.4  to  0.5  cubic  foot  per  hour.  Parkes  adopts  0.6  cubic 
foot  per  hour  as  the  average  for  a  mixed  assemblage,  and  this  seems 
to  be  a  iair  estimate. 

If  now  we  divide  the  amount  of  carbonic  acid  exhaled  in  an  houf  by 
the  limit  of  respiratory  carbonic  impurity  for  good  ventilation,  we  shall 
,  0.6 

V60  0002  ~  3>°°°>  wnicn  is  the  number  of  cubic  feet  of  air  per  hour 

required  per  person,  and  this  is  the  standard  which  is  now  most  com- 
monly accepted  by  English  sanitarians.  In  this  calculation  it  will  be 
seen  that  the  proportion  of  carbonic  acid  in  the  air  as  it  is  delivered 
into  the  room  is  not  considered.  If  this  be  taken  into  the  account, 
Seidel's  formula  is  a  convenient  one,  and  is  as  follows  : 

y  =  2.30258  m.  log.    ~^q 

m  —  volume  of  air  in  the  room  or  enclosed  space. 

p  —  initial  proportion  of  CO3  per  1000. 

q  —  proportion  of  CO2  per  1,000  in  the  fresh  air  introduced. 

•  a  —  proportion  of  CO2  per  i.ooonot  to  be  exceeded  in  a  given  time. 

y  —  the  volume  of  fresh  air  to  be  brought  in  so  that  the  proportion  of 
CO 3  in  the  mixture  shall  not  exceed  a. 

If  the  time  be  five  hours,  the  cubic  space  20  meters,  the  CO2  in  the 
initial  and  fresh  air  be  0.4  per  1,000  and  the  limit  of  CO2  be  0.7  per 
1,000,  thenjy  =  100  cubic  meters,  or  3,533  cubic  feet.  In  this  calcu- 
lation the  amount  of  expired  CO2  is  taken  as  20  litres  ^0.706  cubic  feet 
per  hour). 

In  the  eighth  edition  of  Parkes'  Hygiene,  p.  186,  the  amount  of 
CO2  evolved  during  repose,  is  given  as  follows  : 

*Text  Book  of  Human  Physiology.     Philadelphia,  1889,  p.  233. 


124 


QUANTITY  OF  AIR  REQUIRED. 


' '  Adult  males      (say  1 60  pounds  weight) (. ...  o.  72  of  a  cubic  foot. 

"      females  (  "    120       "  "      ).... 0.6        "        " 

Children  ("      80       •'  )     0.4 

Average  of  a  mixed  community 0.6        " 

Under  these  conditions  the  amount  of  fresh  air  to  be  supplied  in 
health  during  repose,  ought  to  be  : 

"  For  adult  males 3, 600  cubic  feet  per  head  per  hour,  102  c.m. 

females 3,000  "f  "  "  85     " 

"Children 2,000  57     " 

"  a  mixed  community,  3  ooo  "  85     " 

The  amount  for  adult  males,  as  above  given,  is  just  over  100  cubic 
meters,  or,  if  we  state  it  at  3,600  cubic  feet,  it  is  just  i  cubic  foot  per 
second." 

The  above  figures  with  regard  to  quantity  of  air  required  for  ven- 
tilation are  in  strong  contrast  to  those  given  in  some  engineering 
manuals,  and  especially  those  given  by  Box,  which  appear  to  be  those 
of  half  a  century  ago.  His  figures  are  contained  in  the  following 
table,  from  which  he  concludes  that  in  a  room  very  thinly  occupied,  250 
cubic  feet  of  air  per  head  per  hour  is  sufficient,  and  that  for  crowded 
assembly  rooms,  500  cubic  feet  per  hour  is  the  proper  allowance. 

Box's  TABLE  OF  CUBIC  FEET  OF  AIR  REQUIRED  FOR  THE  DIFFERENT  PUR- 
POSES OF  VENTILATION. 


Character  of  Occupants. 

For  Res- 
piration. 

For 
Vapor. 

For  Ex- 
halations 

For 
Heat. 

For 

Lights. 

Room  with  one  clean  and  healthy  ) 
occupant        ....                \ 

22 

237 

250 

22O 

60 

Room  with  one  healthy,  but  not  [ 
clean  occupant.     .                       ) 

22 

237 

350 

220 

60 

Room  with  one  sick  man  
Crowded    room,     healthy    and  \ 
cleanly  persons  f 

22 
22 

237 
237 

I.OOO 
250 

220 
500 

60 
60 

Hospitals  (ordinary)  

22 

237 

2,000 

2  2O 

60 

Hospitals  (fever)  

22 

237 

4,000 

22O 

60 

It  should  be  observed  that  the  same  air  serves,  simultaneously  or 
consecutively,  for  all  the  five  purposes  assigned.1 

Taking  the  allowance  of  250  cubic  feet  per  hour,  and  the  amount 
of  carbonic  acid  exhaled  by  one  person  at  0.6  cubic  foot  per  hour,  we 
should  find  that  at  the  end  of  the  second  hour  in  an  ordinary  sized 
room  the  proportion  of  carbonic  acid  in  the  air  of  the  room  would 


1  T.  Box,  A  Practical  Treatise  on  Heat.     7th  Ed.,  1891,  p.  245. 


QUANTITY  OF  AIR  REQUIRED.  125 

have  risen  from  4  parts  in  10,000,  to  24  parts  in  10,000,  while  in  the 
crowded  assembly  room,  with  500  cubic  feet  allowance  per  head,  at  the 
end  of  15  minutes  the  proportion  of  carbonic  acid  would  become  12 
parts  per  1,000.  In  either  case,  an  offensive  musty  odor  would  be  pro- 
duced. There  are  several  sources  of  error  in  the  calculations  of 
Tredgold  and  Peclet  which  are  adopted  by  Box  in  the  above  table. 
In  the  first  place,  they  assume  that  the  used  and  contaminated  air  does 
not  mix  with  and  defile  the  air  in  the  room,  but  passes  off  to  a  separate 
place.  If  each  person  inhaled  air  from  one  reservoir,  and  expired  it 
into  a  totally  different  one,  the  table  would  have  some  value,  but  this 
is  only  the  case  when  a  man  is  working  in  the  armor  of  a  submarine 
diver,  or  something  of  that  kind. 

The  second  error  involved  is  one  of  observation,  in  the  supposition 
that  all  the  air  entering  a  given  room  came  through  the  ventilating  flue. 
For  example,  Peclet  states  that  in  a  public  school  of  180  children,  of 
seven  or  eight  years,  only  a  slight  odor  was  perceptible  when  212 
cubic  feet  of  air  per  head  per  hour  was  supplied,  and  that  in  a  prison 
cell  with  the  same  supply  there  was  a  sensible  odor  which  disappeared 
entirely  when  350  cubic  feet  were  supplied. 

These  are  almost  impossible  figures,  and  it  is  nearly  certain  that  a 
very  large  amount  of  ventilation  must  have  been  going  on  in  these 
rooms  through  diffusion  and  leakage  of  which  Peclet's  measurements 
in  the  flue  give  no  trace.* 

*  In  this  connection  the  following  account  of  an  experiment  made  by  Mr. 
Putnam,  to  test  the  amount  of  air  which  passes  through  the  pores  and  acci- 
dental fissures  of  an  ordinary  living  room,  will  be  found  of  interest.  The 
room  was  about  5  meters  square  and  3  6  meters  high,  having  five  windows, 
two  doors  and  a  fireplace,  with  plastered  walls  and  ceiling  and  a  soft  pine 
floor. 

"A  flue  10  meters  long,  from  a  basement^furnace,  furnished  the  rooms 
with  hot  air.  The  windows  and  doors  were  first  made  as  tight  as  possible 
with  rubber  moldings.  The  fireplace  was  then  closed  by  drawing  the  damper 
and  pasting  paper  over  the  cracks.  The  brick  back  and  jambs  were  oiled 
to  render  them  impervious.  All  the  woodwork  was  thoroughly  oiled  and 
shellacked.  A  good  fire  was  lighted  in  the  furnace,  and  the  register 
opened  into  the  room,  all  doors  and  windows  being  closed  and  locked, 
and  the  keyholes  stopped  up.  The  hot  air  entered  almost  as  rapidly  with  the 
doors  closed  as  when  they  stood  open,  and  "it  continued  to  enter  at  the  rate  of 
2.5  cubic  meters  per  minute  without  diminution  as  long  as  the  experiment  was 
continued.  The  thermometer  stood  at  2°  C.  outside.  The  entering  hot  air 
ranged  from  40°  to  55°  C.  The  day  was  March  3,  1880.  Other  experiments 
gave  the  same  results.  The  pressure  of  the  hot  air  from  the  register  was 
sufficient  only  to  raise  a  single  piece  of  cardboard  from  the  register.  A 


126 


QUANTITY  OF  AIR  REQUIRED, 


The  third  error — which,  however,  is  common  to  many  estimates 
by  physicians  as  well  as  by  engineers,  is  the  supposition  that  the  exhala- 
tions from  a  sick  person  are  from  4  to  12  times  as  great  as  from  a 
person  in  health.  This  error  was  due  to  the  fact  that  the  cause  of  the 
infection  of  hospital  wards  was  not  understood,  and  it  was  supposed 
that  the  contagious  matters  existed  in  the  form  of  gas  or  vapor  instead 
of  being  particulate,  as  we  now  know  that  many  of  them  are. 

General  Morin's  estimates,  which  are  frequently  quoted,  but  which 
Box  erroneously  criticises  as  being  in  many  cases  excessive,  are  shown 
by  the  following  table  : 


PLACES  VENTILATED. 

CUBIC  FEET  OF  AIR  PER 
HEAD  PER  HOUR. 

Max. 

Min 

Mean. 

Hospitals  ordinary  maladies 

2,470 

3,530 
5,300 

1,585 
2,I2O 
I.,76o 
2.I2O 
3,530 
1,  060 
1,760 

618 

T.235 

6,700 

"          wounded,  etc  . 

"          in  times  of  epidemic          .  . 

Theaters                                      

1,760 

1,410 

Assembly  rooms,  prolonged  sittings  

Prisons                      

Workshops,  ordinary  

'  '             insalubrious    

Barracks,  during  the  day  

"              "        "    night 

Schools,  infant 

706 
1,410 
7,060 

530 
1,  060 
6,350 

'  '       adult 

Stables  

portion  of  the  air  must  have  passed  through  the  pores  of  the  materials,  and 
the  rest  through  cracks  and  fissures  which  escaped  detection.  On  the  5th  of 
March  a  coat  of  oil  paint  was  applied  to  the  walls  and  ceilings.  This  dimin- 
ished the  escape  of  air  only  about  5  per  cent.  On  the  igth  of  March  four  coats 
of  oil  paint  had  been  put  on  the  walls  and  ceilings,  and  three  coats  on  the  floor, 
to  render  them  absolutely  impervious  to  air.  The  escape  of  air  was  diminished 
only  about  10  per  cent.  On  the  25th  of  March  all  the  window  sashes  were  care- 
fully examined,  and  all  visible  cracks  at  the  joints,  at  the  pulleys,  cord  fasten- 
ings, etc.,  carefully  calked  and  puttied,  and  the  entire  room  examined,  and 
putty  used  freely  wherever  even  a  suspicion  of  crack  could  be  found.  The 
result  of  all  this  was  a  diminution  at  the  utmost  of  but  20  per  cent,  in  the 
escape  of  the  air,  or,  in  other  words,  in  the  entrance  of  air  through  the  register. 
Each  experiment  was  continued  during  more  than  an  hour.  The  air  entered 
as  freely  at  the  end  as  at  the  beginning  of  the  hour,  when  a  volume  of  air 
more  than  equal  to  the  entire  capacity  of  the  room  had  entered  it  through  the 
register,  with  no  visible  outlet."  J.  Pickering  Putnam.  The  Open  Fireplace 
in  all  Ages,  Boston,  1881,  p.  137. 


QUANTITY  OF  AIR  REQUIRED.  127 

The  point  of  view  from  which  some  heating  engineers  consider 
this  question  of  air  supply  is,  as  expressed  by  one  of  them,  that  "the 
whole  matter,  then,  resolves  itself  into  opinions  as  to  individual  per- 
sonal comfort,  and  to  observations  upon  healthfulness  of  some  of  the 
very  few  rooms  and  places  where,  for  a  period  of  time  more  or  less 
extended,  a  definite  ventilation  has  been  maintained."  He  then  goes 
on  to  say  that  30  cubic  feet  of  air  per  person  per  minute  is  sufficient ; 
that  "anything  may  be  called  tolerable  that  is  tolerated;  anything  may 
be  esteemed  endurable  that  is  endured.  Churches,  halls,  schools, 
theaters,  state-houses,  court-rooms,  etc.,  are  rendered  tolerable  when 
judicious  care  is  taken  in  changing  the  air  after  a  session,  and  in  hav- 
ing fresh  air  in  the  audience  rooms  at  the  commencement  of  the  same. 
They  are  endurable.  Not  only  can  little  illness  or  actual  disease  be 
traced  to  them  as  places  of  origin,  but,  on  the  whole,  the  audiences 
accustomed  or  habituated  to  the  closeness  of  the  air  which  accompanies 
any  lengthened  session,  cease  to  notice  what  would  be  excessively  dis- 
agreeable to  the  newcomer  entering  the  confined  room.  People  do  not 
willingly  find  fault  when  there  is  apparently  no  remedy.  Perhaps  the 
most  striking  example  of  this  salutary  effect  of  occasional  change  of 
air,  as  a  substitute  of  ventilation  by  constant  supply,  is  to  be  found  in 
our  American  railroad  cars,  where,  in  cold  weather,  the  least  amount 
of  regular  supply  is  furnished  to  the  largest  number  of  persons  tem- 
porarily crowded  into  the  smallest  space.  To  the  outsider  the  heat 
becomes  intolerable  ;  to  the  insider  it  is  more  endurable  than  any 
draught  of  fresh,  cold  air.  The  unhealthful  condition  of  the  car  dur- 
ing six  months  of  the  year  cannot  be  questioned;  and  yet  no  serious 
illness  that  can  be  attributed  to  the  want  of  ventilation  is  found  among 
the  tens  of  thousands  of  passengers;  and  it  is  well  known  that  the  con- 
ductors, brakemen  and  others  connected  with  the  trains,  who  live  in 
and  out  of  the  cars  from  day  to  day,  are  healthy  beyond  the  healthful- 
ness  of  most  other  men." 

While  there  is  a  certain  amount  of  truth  in  these  statements,  the 
whole  impression  conveyed  by  them  to  the  average  reader  is  certainly 
incorrect.  Thirty  cubic  feet  of  air  per  minute,  in  rooms  continuously 
occupied,  will  not  secure  good  ventilation  ;  nor  is  an  architect  or  en- 
gineer justifiable  in  preparing  plans  upon  the  basis  of  such  an  amount 
of  supply. 

Under  such  circumstances  the  air  will  become  markedly  foul,  and 
will  exercise  a  very  deleterious  influence  upon  the  health  of  the  occu- 
pants, who  will  be  especially  liable  to  consumption  and  allied  diseases 
if  they  continue  to  remain  in  it  for  a  length  of  time,  and  who  will'suffer 


128  QUANTITY  OF  AIR  REQUIRED. 

from  headache,  loss  of  appetite,  want  of  energy,  etc.,  from  even  a  con- 
paratively  short  exposure  to  such  a  vitiated  atmosphere  as  this  in- 
sufficient supply  will  produce. 

Every  one  who  has  had  any  practical  experience  in  investigating 
the  condition  as  to  ventilation  of  assembly  halls,  hospitals,  schools, 
etc.,  knows  that  personal  omnions  as  to  the  condition  of  the  air  at  a 
given  time  differ  widely.  One  statesman  will  declare  the  air  of  his 
legislative  chamber  to  be  foul  and  pernicious  at  the  very  time  when 
several  others  will  say  that  it  seems  pure  and  satisfactory,  and  the  ad- 
vocate of  some  special  method  of  heating  and  ventilating  will  invari- 
ably find  the  results  produced  by  that  method  to  be  better  than  most 
other  observers  will  admit  them  to  be. 

Attempts  to  lower  the  standard  of  air  supply  which  has  been 
established  by  the  'experiments  and  observations  of  physiologists, 
sanitarians,  and  vital  statisticians,  on  the  plea  of  demanding  positive 
evidence  as  to  the  actual  results  which  foul  air  produces,  or  that  air 
which  is  foul  to  a  certain  extent  does  not,  in  many  instances,  produce 
any  perceptible  results,  must  be  considered  as  unwise. 

Precisely  the  same  argument  will  apply  to  almost  all  measures 
which  are  recommended  by  sanitarians.  In  how  many  houses,  for  ex- 
ample, is  gas  from  the  sewers  or  from  foul  soil  pipes  escaping  through 
pan  closets,  etc.,  without  producing  observed  ill  effects?  And  yet  is 
that  to  be  taken  as  a  sufficient  reason  for  abandoning  efforts  to  secure 
ventilated  soil  pipes  and  properly  arranged  traps?  The  above  argu- 
ment is  one  that  will  be  eagerly  seized  upon  by  those  who  have  paid 
no  attention  to  provisions  for  heating  and  ventilation  for  schools,  as 
an  excuse  for  their  ignorance,  negligence,  or  parismony,  and  will  be 
perverted  to  uses  of  which  the  author  probably  did  not  dream  in  writ- 
ing it. 

The  conclusion  "that  for  audience  halls  occupied  for  sessions  not 
exceeding  two  or  three  hours'  duration,  Dr.  Reid's  value  of  10  cubic 
feet  of  air  per  minute  per  person  *  *  *  is  all  that  should  be 
arranged  for  when  planning  such  halls  ;  all  that  can  be  judiciously 
urged  in  the  accomplishment  of  ventilation,  in  view  of  the  cost  of  fuel 
and  apparatus  ;  quite  sufficient  to  meet  the  physiological  issue,  and  so 
large  that  it  ought  to  be  accepted  from  the  medical  point  of  view,"  is 
one  that  we  must  most  positively  deny.  The  amount  of  supply  for  such 
halls  should  in  no  case  be  less  than  30  cubic  feet  of  air  per  minute 
through  the  regular  flues  of  supply,  and  in  legislative  buildings  the 
apparatus  should  be  such  that  at  least  45  cubic  feet  of  air  per  person 
per  minute  can  .be  furnished,  with  a  possibility  of  increasing  it  to  60 


QUANTITY  OF  AIR  REQUIRED.  129 

feet  per  minute  when  desired.  In  dealing  with  such  matters  as  air  and 
water  supply,  engineers  should  endeavor  to  secure  maximum  and  not 
minimum  quantities'. 

No  architect  or  engineer  would  advise  making  plans  to  corre- 
spond with  the  requirement  of  10  cubic  feet  per  minute  per  person,  if  the 
question  of  expense  of  construction  and  maintenance  did  not  come  in; 
and  the  difference  between  the  opposing  views' is  in  the  main  that  one 
considers  the  question  of  cost  as  more  important  than  others  are  dis- 
posed to  do,  So  far  as  construction  is  concerned,  the  difference  in  cost 
between  providing  for  an  air  supply  of  10  and  one  of  60  cubic  feet  per 
minute  will  not  often  be  so  great  as  to  be  a  serious  objection, provided 
the  plans  be  made  before  the  construction  of  the  building  is  commenced. 

It  is^when  we  have  to  provide  heating  and  ventilating  arrange- 
ments for  existing  buildings  which  have  been  planned  in  utter  ignor- 
ance of  the  requirements  of  heating  and  ventilation — and  this  is  the 
case  with  at  least  one-half  of  our  largest  and  most  costly  buildings,  that 
we  have  to  diminish  the  supply  of  fresh  air  to  the  smallest  permissible 
amount  in  order  to  be  allowed  to  introduce  any  at  all.  The  ventila- 
tion of  such  buildings  cannot  be  made  satisfactory  ;  it  is  only  "  en- 
durable," and  a  ventilation  which  is  only  just  "  endurable  "  is  discredit- 
able to  the  architect  of  the  building  in  which  it  occurs,  provided  that 
his  advice  has  been  followed  on  this  point. 

-  Some  of  the  differences  in  air  supply  required  will  be  referred  to 
in  the  chapters  on  the  ventilation  of  different  classes  of  buildings,  of 
mines,  etc.  In  planning  new  buildings  of  a  permanent  character  the 
architect  should  not  rely  on  leakage  through  crevices  or  on  bad  con- 
struction of  the  building  as  a  source  of  air  supply.  It  should  be 
assumed  that  the  walls  will  be  rendered  more  or  less  impermeable  by 
paper,  paint,  etc.,  and  that  all  the  fresh,  air  is  to  enter  through  the 
ducts  provided  for  that  purpose.  Under  these  circumstances  the 
flues,  registers,  heating  apparatus,  fans,  etc.,  should  be  adjusted  to  the 
following  scale  of  air  supply: 


Cubic  Feet  of  Air  per  Hour. 


Hospitals , 

Legislative  assembly  halls 

Barracks,  bedrooms,  and  workshops. . .  . 

Schools  and  churches .^ 

Theaters  and  ordinary  halls  of  audience 

Office  rooms 

Water  closets  and  bath  rooms 

Dining  rooms 


3,600  per  bed. 
3,600  per  seat. 
3,000  per  person. 
2,400  per  person. 
2,000  per  seat, 
i, 800  per  person. 
2,400  each, 
i, 800  per  person. 


130  QUANTITY  OF  AIR  REQUIRED. 

If  this  be  done  it  will  be  comparatively  easy  to  adjust  the  appli- 
ances to  a  less  amount  of  supply  if  the  occupant  be  unwilling  to  pay 
for  the  heating  and  moving  of  the  proper  amount,  whereas  if  they  are 
planned  for  the  "tolerable"  or  "  endurable"  minimum  supply,  it  will 
be  impossible  for  them  to  meet  the  larger  demands  which  the  educated 
and  thinking  portion  of  the  community  are  beginning  to  make,  and 
which  will  steadily  increase. 

If  it  is  a  question  of  ventilating  old  buildings,  where  the  difficul- 
ties are  great  and  minimum  amounts  only  can  be  provided,  furnishing 
jvhat  has  been  called  the  air  supply  of  endurance,  the  above  figures 
may  be  reduced  one-half,  but  it  should  be  clearly  understood  that  if 
this  be  done  the  results  will  not  be  altogether  satisfactory,  and  some 
odor  will  be  perceived,  although  no  demonstrable  injury  to  health  may 
be  produced.  Of  course,  under  circumstances  which  permit  the  ob- 
taining of  larger  amounts  than  those  above  specified  without  materially 
increasing  the  cost  it  should  be  done. 

In  the  open  air,  with  the  temperature  at  60°  F.,  and  when  there  is 
no  perceptible  wind,  about  32,400  cubic  feet  of  air  per  hour  will  flow 
over  or  come  in  contact  with  the  person  of  a  man  supposing  his  body 
to  present  an  area  of  about  9  square  feet,  and  the  displacement  of 
air  to  be  at  the  rate  of  i  foot  per  second.  In  comparison  with  this, 
the  allowance  of  3,600  feet  per  hour  certainly  seems  insignificant.  It 
should  be  remembered,  however,  that  this  is  the  cold-weather  allow- 
ance, when  the  incoming  air  must  be  warmed,  and  that  in  summer  the 
amount  should  be  increased  as  much  as  possible,  since  to  do  so  does 
not  produce  increased  cost. 

For  about  six  months  in  the  year  the  air  may  be  allowed  to  sweep 
freely  through  inhabited  rooms,  and  the  architect  may  do  much  to 
secure  facilities  for  its  doing  so  more  commonly  than  is  usually  the 
case.  We  shall  allude  to  this  again  in  speaking  of  methods  of  distri- 
bution, and  the  subject  of  amount  of  air  supply  will  also  receive  further 
consideration  when  we  come  to  speak  of  assembly  halls. 

The  amount  of  air  required  for  animals  has  not  received  much 
investigation. 

F.  Smith,  in  his  Manual  of  Veterinary  Hygiene  (London,  1887,  p. 
67),  states  that  a  horse  exhales  about  6.5  cubic  feet  of  CO2  per  hour, 
and  adopting  two  parts  of  CO2  per  10,000  of  air  as  the  limit  of  permis- 
sible respiratory  impurity,  he  concludes  that  in  stables  32,500  cubic 
feet  of  air  should  be  supplied  for  each  horse  per  hour. 

This  is  a  much  larger  quantity  than  that  indicated  by  other 
writers.  Marker  estimates  that  from  i  to  1.5  cubic  feet  of  air  per 


QUANTITY  OF  AIR  REQUIRED.  13! 

hour  for  each  pound  in  weight  of  the  animal  is  sufficient,  but  this  is 
certainly  much  too  small  an  allowance. 

In  Dr.  Carl  Dammann's  work,  Die  Gesundheitspflege  landwirt- 
schaftlicher  Haussaugetiere,  2d  edition,  Berlin, 1892,  p.  677,  he  estimates 
that  a  cow  or  a  horse  weighing  1,000  pounds  should  have  50  cubic 
meters  of  air  per  hour  for  ventilation. 

k 

He  uses  the  formula  y=  ,y  being  the  amount  of  air  in  cubic 

p  —  q 

meters  required  per  hour,  k  the  amount  of  carbonic  acid  exhaled  by 
the  animal  per  hour,/  the  limit  of  impurity  of  carbonic  acid  contents 
of  the  air  in  the  stable,  and  q  the  carbonic  acid  contents  of  the  outer 
and  incoming  air.  For  smaller  animals  he  estimates  that  the  supply 
should  be  60  cubic  meters  per  hour  per  1,000  pounds  of  animal. 

On  page  08 1  he  alludes  to  the  effect  of  good  ventilation  in  increas- 
ing the  quantity  of  milk  given  by  cows  ;  for  example,  in  a  cow  stable 
at  Frankfort-on-the-Main  were  80  Swiss  cows;  for  the  years  1877  to 
1879,  inclusive,  the  average  production  per  head  was  3,700  litres  of 
milk.  Good  ventilation  was  then  introduced,  and  the  figures  per  head 
of  milk  became: 

In  the  year  1880 , 4,050  litres. 

"    "       "      1881 4,152     " 

"    "       "      1882 4,355     " 

This,  however,  would  require  confirmation,  and  the  increase  in 
quantity  of  milk  should,  moreover,  be  compared  with  the  extra  expense 
for  warming  and  for  an  increased  quantity  of  food,  which  was  no  doubt 
incurred  in  connection  with  the  extra  production. 

Small  animals  require  more  air  in  proportion  to  their  weight  than 
large  ones,  and  the  so-called  wild  animals  more  than  those  which  have 
been  domesticated.  Monkeys  require  a  comparatively  liberal  allow- 
ance of  fresh  air  to  keep  them  in  good  health. 

Thus  far,  in  speaking  of  the  quantity  of  air  required,  we  have  been 
considering  only  the  need  for  diluting  and  removing  the  products  of 
animal  exhalation,  and,  for  ordinary  living  rooms,  the  amount  that  is  suf- 
ficient for  this  is  sufficient  for  the  other  purposes  for  which  it  is  required  in 
human  habitations — /.  e.,  to  support  the  combustion  pf  fires  and  lights,  to 
remove  moisture,  etc.  If  the  number  of  lights  be  large  in  proportion  to 
the  number  of  persons,  it  may  be  desirable  to  provide  a  special  supply 
of  air  to  dilute  the  products  of  their  combustion,  and  more  especially  to 
prevent  an  undue  rise  of  temperature.  A  cubic  foot  of  ordinary 
illuminating  gas  when  burned  produces  about  2  cubic  feet  of  car- 
bonic acid,  and  a  common  gas  burner  will  burn  between  2  and  3  cubic 
feet  of  gas  per  hour. 


132  CUBIC    SPACE. 

The  carbonic  acid  thus  produced  is  not  in  itself  of  much  sanitary 
importance  under  ordinary  circumstances,  and  in  the  TJnited  States  it 
is  rare  that  other  substances,  such  as  sulphur  dioxide,  are  formed  in 
sufficient  quantity  to  be  annoying.  Wolpert  estimates  that  1,800  cubic 
feet  of  air  should  be  supplied  lor  every  cubic  foot  of  gas  consumed — 
and  this  estimate  is  approved  in  the  last  edition  of  Parkes'  Hygiene, 
which  would  imply  that  over  4,000  cubic  feet  of  air  per  hour  should  be 
furnished  for  every  gas  burner.  One-fourth  of  this  amount  is  probably 
ample.  In  assembly  halls,  theaters,  etc.,  the  electric  light  is  now  tak- 
ing the  place  of  gas,  and  of  course  requires  no  provision  for  air  supply. 

In  exceptional  cases  the  amount  of  air  supply  is  to  be  calculated 
with  reference  to  its  being  a  medium  for  the  conveyance  of  heat.  If, 
for  example,  a  room  is  to  be  warmed  by  heated  air,  the  so-called 
method  of  indirect  radiation,  a  certain  amount  of  air  must  be  supplied, 
even  if  the  room  is  unoccupied  by  human  beings.  The  amount  of  air 
required  for  this  purpose  depends  on  the  temperatures  required — 
amount  of  exposed  wall  and  window  surface,  amount  of  leakage 
around  doors  and  windows,  etc.  — but  the  usual  rough  estimate  is  that 
it  should  be  per  hour  about  one  and  a-half  times  the  number  of  cubic 
feet  contained  in  the  room  to  be  thus  warmed.  Unless  this  amount  of 
change  be  secured  when  the  external  temperature  is  below  the  freezing 
point,  either  the  room  will  not  be  kept  comfortably  warm  or  the 
incoming  air  must  be  introduced  at  a  much  higher  temperature  than  is 
desirable.  This  rule  will  not  apply  to  very  lofty  rooms  where  the 
heated  air  will  accumulate  near  the  ceiling,  leaving  the  floor  cold. 

The  higher  the  external  temperature  the  more  air  is  required  to 
secure  comfort,  up  to  the  point  when  the  air  becomes  so  warm  and 
moist  that  it  no  longer  serves  to  remove  the  animal  heat.  In  a  hot, 
moist  summer  day,  sufficient  ventilation  cannot  be  secured  even  out  of 
doors,  especially  if  a  crowd  be  collected. 

Some  heating  engineers  are  in  the  habit  of  making  all  their  calcu- 
lations as  to  amount  of  air  supply  with  reference  to  the  frequency  with 
which  the  air  in  the  room  is  to  be  changed — and  will  say  that  they  pro- 
pose to  change  all  the  air  in  the  room  three,  or  four,  or  six  times  per 
hour,  instead  of  calculating  the  number  of  cubic  feet  required  for  the 
number  of  persons  in  the  room. 

This  is  not  a  satisfactory  mode  of  calculating  or  stating  the  re- 
quirements, because  of  the  great  variations  in  cubic  space  per  person  in 
different  classes  of  rooms. 

Cubic  space  is  an  important  factor  in  ventilation  in  seme  cases, 
while  in  others  it  is  of  very  secondary  importance. 


'CUBIC    SPACE.  133 

The  most  valuable  paper  on  this  subject  is  the  "  Report  of  the 
committee  appointed  to  consider  the  cubic  space  of  Metropolitan 
Workhouses,"  published  in  folio  as  a  parliamentary  blue-book  in  1867. 

This  contains  papers  by  Drs.  Acland,  Angus  Smith,  Markham, 
Parkes,  Donkin  and  others,  in  which  the  matter  is  fully  discussed. 

Assuming  that  the  harmful  matters  in  the  air  of  an  occupied  room 
are  constantly  and  equably  produced,  and  are  uniformly  diffused — 
and  may  be  represented  by  the  carbonic  acid  present,  Professor  Donkin 
gives  the  following  formula: 

P         P  At 

x  =  ^  +  A  ~  A   2-7i8— —     m  which 

x  is  the  number  of  units  of  CO3  per  cubic  foot  in  the  air  of  the 
room  at  the  end  of  /  hours. 

P  is  the  number  of  units  of  CO2  produced  in  the  room  per  hour 
when  it  is  occupied. 

A  is  the  number  of  cubic  feet  of  fresh  air  per  hour  introduced 
(and  also  the  volume  of  air  escaping  during  the  same  time). 

/  is  the  number  of  units  of  CO2  per  cubic  foot  in  the  fresh  air  in- 
troduced. 

c  is  the  number  of  cubic  feet  in  the  room. 

The  numercial  value  of  the  last  term  in  the  equation  diminishes 
rapidly  as  /  increases  and  becomes  insensible.  After  a  number  of 
hours  depending  on  the  ratio  of  A  to  C,  the  final  value  becomes: 

P  P 

x=p  +  -  whence  A  =  ~^^p 

For  example:  suppose  a  man  produces  6.units  of  carbonic  acid  per 
hour,  and  fresh  air  contains  .004  such  units  per  cubic  foot ;  if  it  is  re- 
quired to  maintain  a  room  (of  whatever  size),  constantly  occupied  by 
one  man,  in  such  a  condition  that  the  units  of  carbonic  acid  in  a  foot 
shall  never  exceed  .006,  then 

A  - =  3,000, 

.006  —  .004 

that  is  3,000  cubic  feet  of  fresh  air  must  be  supplied  per  hour. 

In  this  case,  at  the  end  of  /  hours  after  the  room  begins  to  be  oc- 
cupied, the  number  of  units  of  carbonic  acid  per  cubic  foot  is 

3.000  / 
.000  —  .002  X   G  — 

where  c  is  the  number  of  cubic  feet  in  the  room. 

Thus,  suppose  the  room  contains  1,000  cubic  feet,  then  the  units 
of  carbonic  acid  per  cubic  foot  are, 


134  CUBIC    SPACE. 

At  first  ..............  .  ..........................  .    .  .004 

After  i  hour  .........................................  005900 

"     2  hours  .......................................  005995 

"     3      "        .....................................  0059997 

so  that  after  two  hours  the  room  would  have  sensibly  reached  the  final 
condition  of  .006  units  per  cubic  foot.  If  the  room  contained  only  100 
cubic  feet,  the  approximation  to  the  final  state  would  be  much  more 
rapid.  His  conclusion  is  that,  uniform  diffusion  being  supposed,  the 
same  supply  of  air  will,  after  a  short  time,  equally  ventilate  any  space. 
The  assumption  of  uniform  diffusion  is  rarely  correct  in  any  given 
case,  because  the  diffusion  of  gases  does  not  go  on  so  rapidly  as  to 
overcome  the  effects  of  currents  of  air  produced  either  by  mechanical 
means  or  by  different  temperatures,  and  such  currents  almost  always 
exist  in  a  room  occupied  by  men,  so  that  marked  differences  may  thus 
be  produced  in  the  composition  of  the  air  in  different  parts.  Usually 
the  upper  strata  will  contain  a  little  more  carbonic  acid  and  watery 
vapor.  The  formula  for  the  amount  of  fresh  air  necessary  to  reduce  a 
vitiated  atmosphere  to  a  required  standard  of  purity  is  given  by  De 
Chaumont  as  follows  : 

Let  R  be  the  r?tio  of  carbonic  acid  in  incoming  air. 

"    r'    "         "  "  "     vitiated  air. 

"    c    be  the  capacity  of  original  air  space  in  cubic  feet. 

"    r    be  the  desired  ratio  of  purity  to  which  r  is  to  be  reduced. 

"    d   be  the  delivery  of  fresh  air  in  cubic  feet. 

"    v    be  the  total  volume  of  air,  c  -f  d. 

Then:  ^_  x  c  —  v,  and  v—  c  —  d. 

T  —  R 

It  will  be  at  once  seen  by  the  above  formula  that  when  r  =  R,  that 
is,  when  it  is  wished  to  restore  c  to  the  purity  of  the  external  air,  v  and 
d  become  infinity,  so  that  complete  purification  of  c  is,  under  these 
circumstances,  theoretically  impossible. 

To  determine  the  number  of  men,  «,  a  cubic  space,  c,  will  accom- 
modate, we  have  the  following,  r  and  R  being  the  ratio  per  cubic  foot, 
e  the  CO2  expired  by  one  man  in  an  hour  (  =  .6  cubic  feet),  and  h  the 
number  of  hours: 


= 


eh 

To  determine  the  delivery  of  air  required  to  maintain  an  unoccu- 
pied space  at  a  given  ratio  of  purity,  r,  we  have: 

n  e  h 

~n —  v,  and  v — c=.d. 


CUBIC    SPACE. 


135 


In  computing  cubic  space  for  purposes  of  ventilation,  heights  of 
rooms  above  12  feet  should  be  disregarded.  With  this  limitation  the 
minimum  amount  of  cubic  space  which  should  be  given  may  be 
stated  as  follows: 

In  a  common  lodging  or  tenement  hous*3 300 

In  a  school- room 250 

In  a  barrack  dormitory  for  soldiers  or  police 600 

In  an  ordinary  hospital  ward 1,000 

In  a  fever  or  surgical  ward i  ,400 

Taking  the  standard  of  3,000  cubic  feet  of  air  per  hour  per  head, 
the  following  table  by  Parkes  shows  the  amount  of  air  necessary  to 
dilute  to  this  standard  : 


Amount  of  air  nec- 

Ratio per  1,000  of 

essary  to  dilute  to 

Amount  of  cubic 

carbonic  acid  from 

standard  of  .2,  or  in- 

Amount  necessary 

space  (breathing 
space)  for  one  man, 
in  cubic  feet. 

respiration     at    the 
end  of  one  hour  if 
there   has   been    no 

cluding   the    initial 
carbonic  acid,  of  .6 
per    1,000    volumes 

to  dilute  to  the  given 
standard  every  hour 
after  the  first. 

change  of  air. 

during  the  first  hour 

TOO 

6.00 

2.900 

3,000 

200 

3.00 

2.8oo 

3,000 

300 

2.00 

2.700 

3.000 

4OO 

1.50 

2,6oo 

3,ooo 

500 

i  .20 

2,500 

3,ooo 

600 

1.  00 

2,400 

3,ooo 

700 

0.85 

2,300 

3,000 

800 

0.75 

2,200 

3,000 

900 

0.66 

2.IOO 

3.000 

I,OOO 

0.60 

2  OOO 

3.000 

The  above  table  refers  to  rooms  occupied  for  a  number  of  hours 
consecutively. 

In  any  given  case  the  amount  of  air  required  for  each  room  will 
depend  on  the  dimensions  of  the  room,  the  difference  between  the 
external  and  internal  temperatures,  the  number  of  persons  occupying 
it,  their  character  or  occupation,  and  the  length  of  time  they  are  to 
remain  in  it. 

In  rooms  occupied  for  several  hours,  such  as  bedrooms,  dormi- 
tories, hospital  wards,  etc.,  cubic  space  is  important  mainly  with  refer- 
ence to  the  possibility  of  moving  the  required  amount  of  air  through 
the  room  without  giving  rise  to  unpleasant  currents  or  draughts,  and 
secondarily,  in  reference  to  the  amount  of  wall  space,  cracks,  etc.,  avail- 
able for  the  diffusion  or  leakage  of  air.  In  attempts  to  regulate  the 
air  supply  of  certain  classes  of  people  by  legislation  or  regulation— as 
is  done  for  common  lodging  and  tenement  houses,  and  in  England  for 


136  CUBIC    SPACE. 

soldiers  and  school  children — it  is  always  the  cubic  space  and  not  the 
amount  of  air  supply  that  is  prescribed,  owing  ^probably  to  the  fact 
that  it  is  much  easier  to  determine  the  former  than  the  latter.  With 
air  warmed  to  an  agreeable  temperature,  and  many  inlets  and  outlets 
of  large  aggregate  area  to  ensure  proper  distribution,  and  with  suffi- 
cient mechanical  power  to  ensure  the  requisite  movement,  it  would  be 
possible  to  furnish  the  required  amount  of  air  without  perceptible 
draughts  when  the  cubic  space  was  small.  At  temperatures  of  from 
65°  to  75°  F.,  air  moving  at  the  rate  of  i^  feet  per  second  will  not 
be  felt  as  a  current.  If,  therefore,  in  a  room  10  feet  square  and  high, 
the  floor  and  ceilings  be  made  practically  gratings,  and  air  at  70°  F. 
be  drawn  through  so  as  to  secure  an  uniform  upward  or  downward  cur- 
rent throughout  the  room  having  a  velocity  of  3  inches  per  second, 
we  should  have  25  cubic  feet  of  air  per  second  passing  through 
without  perceptible  current — a  quantity  sufficient  for  the  needs  of 
25  personsr-who,  if  packed  into  such  a  room,  would  have  only 
40  cubic  feet  of  air  space  each.  This  is  of  course  purely  theoretical — 
and,  under  ordinary  circumstances,  in  rooms  of  the  usual  dimensions, 
it  is  not  possible  to  change  the  air  more  than  four  times  per  hour,  and 
if  each  person  is  to  have  3,000  cubic  feet  of  air  per  hour,  he  will  there- 
fore need  750  cubic  feet  of  air  space. 

The  British  army  regulations  allow  600  cubic  feet  of  air  space  per 
head  for  soldiers  in  barracks,  in  lodging  houses  from  240  to  300  cubic 
feet  per  head  are  required,  in  the  London  schools  from  130  to  300  cubic 
feet  must  be  furnished. 

In  this  connection  it  should  be  noted  that  floor  space  must  be 
considered  as  well  as  cubic  space. 

In  hospitals  each  bed  should  have  100  square  feet  of  floor  space 
at  least.  The  space  required  in  stables  was  fixed  by  the  Barrack  and 
Hospital  Improvement  Commission,  at  100  square  feet  of  floor  space 
and  about  1,600  cubic  feet  of  air  space  for  each  horse,  but  this  amount 
is  not  actually  furnished.  In  cow  stables  each  animal  should  have  at 
least  900  cubic  feet  of  air  space  in  order  to  prevent  disease,  and  1,200 
cubic  feet  would  be  a  much  wiser  allowance. 

In  the  report  on  cubic  space  above  referred  to,  Dr.  Angus  Smith 
remarks  that  the  advantage  of  large  spaces  is  that  if  there  is  imper- 
fect ventilation,  the  results  are  less  rapidly  perceived,  that  small 
spaces  require  constant  ventilation,  but  this  can  be  made  satisfactory 
if  the  air  is  of  a  proper  temperature,  and  that  larger  spaces  are  needed 
for  high  than  for  low  temperatures,  the  aim  being  to  change  the  air  as 
often  as  is  compatible  with  warmth. 


CHAPTER  VIII. 

ON    THE    FORCES    CONCERNED    IN    VENTILATION. 

VENTILATION  is  produced  by  the  movement  of  air,  and   such 
movement  is  due  to  some  force,  either  derived  from  what  may 
be  called  the  natural  conditions  of  the  locality,  or  specially  developed 
and  applied  for  the  purpose  of  producing  currents. 

In  ordinary  dwellings,  and  for  almost  all  buildings  where  but  few 
persons  are  gathered  in  each  room,  it  is  unnecessary  to  provide  special 
apparatus  for  forcing  or  increasing  the  movement  of  the  air.  During 
warm  weather,  open  windows'and  doors  afford,  in  most  cases,  sufficient 
change  of  air,  and  in  cold  weather  the  expansion  of  the.  air  by  the  action 
of  the  heating  apparatus  and  the  increase  of  temperature  due  to  the 
bodily  warmth  of  the  tenants,  to  lights,  etc.,  furnish  sufficient  motive 
power  if  the  flues  and  registers  are  of  proper  size  and  rightly  placed. 
To  this  may  be  added  the  effects  of  diffusion  through  the  walls  when 
these  are  not  painted,  papered  or  otherwise  made  impervious,  and  the 
leakage  through  cracks  and  crevices,  which  is  an  important  factor  in 
ordinary  dwellings. 

But  in  this  country  and  climate  there  are  a  certain  number  of  days 
in  the  spring  and  fall  when  it  is  too  warm  to  permit  of  the  use  of  heat- 
ing apparatus,  and  when  there  is  no  wind.  In  halls  of  assembly  of  all 
kinds,  and  especially  in  theaters,  in  hospitals,  in  certain  man^actories 
where  noxious  or  offensive  gases  or  dusts  are  produced,  andA  mines, 
tunnels,  etc.,  it  is  often  very  desirable,  and  sometimes  absolutely  neces- 
sary to  provide  power  sufficient  for  the  movement  of  the  requisite 
quantity  of  air,  which  power  shall  be  independent  of  the  heating  appa- 
ratus. Ventilation  thus  produced  or  assisted  is  by  some  writers  termed 
artificial,  as  opposed  to  what  they  call  natural  ventilation,  but  a  better 
term  for  it  is  forced  ventilation. 

The  power  necessary  to  effect  this  forced  ventilation  may  be  de- 
rived from  the  expansion  of  air  by  heat  specially  applied  for  that  pur- 
pose in  the  outlet  flue  or  chimney,  or  from  fans  or  blowers  driven  by 
machinery,  or  from  jets  of  compressed  air,  or  of  steam,  or  from  a  fall- 
ing stream  of  water.  It  is  also  theoretically  possible  to  produce  the 


138  ASPIRATING    FLUES. 

required  movement  of  air  by  cold  as  well  as  by  heat ;  all  that  is  essential 
being  that  there  shall  be  a  difference  in  temperature  between  the  space 
to  be  ventilated  and  the  outer  air,  and  sufficient  channels  of  communi- 
cation between  the  two. 

Wind  is  a  powerful  ventilating  agent,  either  acting  by  perflation 
through  open  windows  and  doors,  or  by  pressure  against  porous  walls, 
or  by  modifying  the  flow  of  air  through  inlet  and  outlet  flues.  It  is  the 
best  of  all  means  when  artificial  heat  is  not  required,  but  it  is  irregular 
in  its  action,  and  cannot  be  depended  upon  as  a  motive  power.  With 
this  may  be  mentioned  the  force  produced  by  movement  of  the  en- 
closed space  through  the  atmosphere,  as  in  the  case  of  railroad  cars  or 
steamships.  We  shall  consider  this  kind  of  motor  power  hereafter  in 
speaking  of  cowls. 

In  Chapter  II.  we  have  spoken  of  some  of  the  physical  properties 
of  the  air,  and  have  given  the  formulae  for  its  expansion  by  increase  of 
temperature,  and  the  consequent  effects  in  the  form  of  upward  currents. 
We  have  now  to  consider  these  in  their  practical  application  to  chim- 
neys, and  especially  to  chimneys  or  large  upcast  flues  intended,  mainly 
or  exclusively,  to  produce  ventilation  by  the  action  of  a  column  of  air 
which  is  warmer  than  the  surrounding  atmosphere,  and  which  are  com- 
monly termed  aspirating  flues  or  chimneys. 

To  determine  the  volume  of  air  passing  through  a  chimney  in  a 
given  time,  we  wish  to  know  the  area  of  its  cross-section  at  some  given 
point,  and  the  velocity  of  the  current  at  this  point.  If  the  volume  in 
cubic  feet  discharged  per  second  be  designated  by  Q,  the  area  in  square 
feet  by  A,  and  the  velocity  in  feet  per  second  by  V,  then  Q  =  A  x  V. 
If  we  wish  to  determine  the  area  of  the  cross-section  which  a  flue  or 
chimney  should  have,  we  usually  first  determine  the  quantity  of  air 
which  it  is  to  transmit  per  second,  and  then,  assuming  such  figure  for 
the  velocity  as  may  seem  most  economical  and  practical  under  the  cir- 

circumstances,  solve  the  problem  by  the  formula  A  —  ^~ 

In  deciding  as  to  the  figure  for  the  velocity  to  be  used  in  the  above 
formula  in  determining  the  capacity  of  a  chimney  already  built,  or  the 
^area  to  be  given  to  a  chimney  flue  to  enable  it  to  transmit  a  given  quan- 
tity of  air,  the  following  considerations  should  be  kept  in  mind: 

If  the  chimney  is  already  built,  the  velocity  may  be  measured  by 
means  of  an  anemometer,  or  by  observing  the  time  required  for  a  puff 
of  powder  smoke  generated  at  the  bottom  to  escape  at  the  top;  but  for 
openings,  flues  and  chimneys  as  yet  unconstructed,  this  velocity  must 
be  calculated.  The  calculation  cannot  be  made  accurate,  as  we  shall 


ASPIRATING    CHIMNEYS.  139 

see,  but  very  useful  results  may  be  obtained  from  it.  The  theoretical 
velocity,  when  friction  is  not  taken  into  account,  is  calculated  in  sev- 
eral ways,  but  that  which  is  now  most  commonly  used  depends  upon 
what  is  known  as  the  law  of  Montgolfier,  or  the  law  of  spouting  fluids. 
This  law  is  that  fluids  pass  through  an  opening  in  a  partition  with 
that  velocity  which  a  body  would  attain  in  falling  through  a  height 
equal  to  the  difference  in  depth  of  the  fluid  on  the  two  sides  of  the 
partition,  or,  what  is  the  same  thing,  the  difference  in  pressure  on  the 
two  sides.  The  velocity  in  feet  per  second  of  falling  bodies  is  about 
eight  times  the  square  root  of  the  height  from  which  they  have  fallen 
expressed  in  feet,  and  the  formula  for  determining  this  is  v  =  c  \/  2  g  h. 

In  this  equation  v  is  the  velocity  to  be  found,  stated  in  feet  per 
second  ;  g  is  the  velocity  which  a  body  falling  freely  from  a  state  of 
rest  has  at  the  end  of  one  second  —  which  is  32.2  feet  per  second  ;  h  is 
the  distance  fallen  through  by  the  body;  and  c  is  a  constant,  determined 
by  experiment,  which  expresses  the  proportion  of  the  actual  to  the 
theoretical  velocity. 

The  height  h,  fallen  through  by  the  cold  air,  is  to  be  determined 
by  the  law  of  the  expansion  of  gases,  which,  for  our  purpose,  may  with 
sufficient  accuracy  be  taken  to  be  ^^  of  its  volume  for  each  degree  F. 
of  increase  of  temperature.  In  the  case  of  a  chimney,  the  force  which 
drives  the  warm  air  up  the  flue  is  the  force  of  gravity,  or  the  excess  of 
gravity  or  weight  of  a  column  of  cold  air  over  a  precisely  similar  column 
of  warm  or  expanded  air,  which  is  the  difference  in  pressure  above 
referred  to. 

This  difference  in  pressure  is  found  by  multiplying  the  height  from 
the  opening  at  which  the  air  enters  the  flue  to  that  from  which  it  escapes 
by  the  difference  between  temperature  outside  and  inside,  and  again 
multiplying  this  product  by  ¥^T.  The  formula  for  the  theoretical 
velocity  then  becomes 

v=S    V  (/-/')  X  h 

491 

in  which  /  is  the  temperature  in  the  chimney,  /'  the  temperature  of  the 
external  air,  and  h  the  height  of  the  chimney. 

Suppose,  for  example,  that  the  temperature  in  the  chimney  is  100 
degrees,  that  of  the  external  air  40  degrees,  and  that  the  chimney  is 
50  feet  high,  we  shall  have 


v  =  8  =  8  v  =  20 

491 

nearly,  or  the  theoretical  velocity  would  be  20  feet  per  second. 


140  CHIMNEYS. 

This  theoretical  velocity  will  be  diminished  by  friction,  by  angles 
in  pipes  and  flues,  and  by  eddies  or  counter  currents,  and  on  the  other 
hand  it  may  be  increased  by  the  aspirating  effect  of  wind  passing  across 
the  top  of  the  flue. 

The  general  rule  is  that  the  real  velocity  in  a  chimney  flue  will  be 
less  than  the  theoretical  velocity  by  from  20  to  50  per  cent.  It  is  be- 
cause of  this  difference  that  minute  calculations  are  useless,  and  that  a 
slightly  inaccurate  formula  is  given  because  of  its  simplicity,  and  the 
ease  with  which  it  can  be  remembered.  From  what  has  been  said,  it  will 
be  seen  that  the  velocity  of  the  ascending  column  of  air  in  a  heated 
chimney  depends  upon  the  difference  in  temperature  between  the  air 
in  the  chimney  and  that  outside.  The  greater  this  difference  up  to 
temperatures  of  800°  F.,  the  greater  the  velocity,  other  things  being 
equal.  The  velocity  also  depends  on  the  height  of  the  chimney,  the 
general  rule  being  that  the  velocity  increases  with  the  height.  This, 
however,  is  neither  theoretically  nor  practically  correct,  except  within 
certain  limits.  The  formula  assumes  that  we  use  in  our  calculations 
the  mean  temperature  of  the  shaft.  It  must  be  remembered  that  there 
is  a  very  considerable  loss  of  heat  from  the  external  surface  of  the 
chimney  itself,  and  the  higher  the  shaft  the  greater  the  amount  of  this 
surface  and  the  greater  the  loss,  thus  neutralizing  to  a  certain  extent 
the  effect  of  the  increase  in  height. 

The  problems  relating  to  velocities  of  currents  and  areas  of  flues, 
more  especially  in  chimneys,  are  comparatively  simple,  if  the  nature  of 
the  force  which  produces  draught  in  a  chimney  be  clearly  understood; 
but  the  popular  mind  is  by  no  means  clear  on  this  point.  Many  per- 
sons seem  to  suppose  that  a  chimney  has  some  independent  power  of 
its  own,  and  in  this  sense  say  that  it  draws  well  or  draws  badly.  A 
mason  has  been  known  to  contend  that  the  chimney  itself  must  do 
some  of  the  work,  independent  of  heat,  because,  in  a  house  which  he  was 
then  at  work  on,  he  found  an  upward  current  in  the  chimney,  although 
the  roof  had  not  yet  been  placed  on  the  building,  and  it  required  several 
trials  under  different  circumstances  to  convince  him  that  this  current 
was  due  to  the  heating  by  the  sun  of  the  south  wall  in  which  the  chim- 
ney was  placed. 

Of  course,  if  a  chimney  had  any  such  power  as  he  supposed,  we 
should  have  a  sort  of  perpetual  motion,  and,  as  Mr.  Edwards  remarks, 
upon  this  theory  it  would  only  be  necessary  to  build  a  few  gigantic 
chimneys  to  work  all  the  mills  in  a  place  without  the  use  of  coal. 

The  velocity  in  a  chimney  should  be  sufficient  to  maintain  a 
steady,  uniform  flow,  without  eddies  or  currents;  and,  at  the  top  of 


CHIMNEYS.  14! 

the  chimney,  it  should  be  so  great  that  the  usual  winds  will  not  inter- 
fere with  it,  which  will  necessitate  a  rate  of  about  10  feet  per  second. 
If  it  be  greater  than  this  there  will  be  a  waste  of  fuel,  for  we  have  seen 
that  this  velocity  depends  upon  the  temperature  to  which  the  air  is 
heated,  and  every  unit  of  heat  contained  in  the  air  escaping  at  the 
mouth  of  the  chimney  which  is  in  excess  of  the  number  of  units  re- 
quired to  prevent  eddies  and  counter  currents,  is  so  much  useless  ex- 
penditure. It  is,  moreover,  quite  unnecessary  to  keep  the  velocity  in 
the  shaft  as  great  as  that  at  the  outlet;  and  it  is  very  poor  economy  to 
do  it,  because  the  friction  increases  rapidly  with  increase  of  velocity, 
and  requires  more  force,  or,  what  is  the  same  thing,  more  fuel,  to  over- 
come it.  The  velocity  in  the  main  flue  of  the  chimney  of  an  ordinary 
dwelling  house  should  be  about  5  feet  per  second  ;  whence  it  follows 
that  the  area  of  opening  at  the  mouth  of  the  chimney  should  be  about 
one-half  that  of  the  main  flue. 

The  increase  of  temperature  in  the  chimney  which  will  be  required 
to  produce  this  velocity  depends,  of  course,  upon  its  height,  but  for  a 
shaft  about  40  feet  high  the  increase  over  that  of  the  external  air 
should  be  at  least  10°  F. 

Of  late  years  the  tendency  of  architects  and  builders  in  this  coun- 
try has  been  to  make  their  flues  too  small,  which  is  probably  due  to  the 
very  general  use  of  stoves.  In  shunning  this  error  care  must  be  taken 
not  to  fall  into  the  opposite  extreme,  for  "  the  expedient  of  construct- 
ing everything  a  little  larger  than  is  necessary  in  order  to  have  a 
reserve  for  contingencies  is  not  always  a  safe  one,"  at  least  if  due  re- 
gard be  given  to  economy.  If  a  chimney  shaft  has  a  larger  area  than 
is  necessary,  down  draughts  will  be  formed  in  it  when  a  sufficient  sup- 
ply of  heated  air  is  not  provided  for  it,  while,  if  this  supply  be  given, 
more  air,  and  therefore  more  heat,  than  is  requisite  must  be  furnished. 
The  us^  of  movable  valves  or  dampers  at  the  base  of  the  shaft  will  pre- 
vent the  last  evil,  but  will  aggravate  the  first;  and  the  same  is  true  as 
regards  the  very  commcn  expedient  of  a  valved  opening  at  the  base  of 
the  shaft  to  allow  air  from  the  boiler  room  to  enter  the  chimney  direct, 
and  therefore  diminish  the  draught.  If  the  valve  be  placed  at  the  top 
of  the  shaft  both  evils  may  be  corrected  within  certain  limits,  and  such 
valves  will  sometimes  be  found  of  great  use. 

The  shape  of  the  flue  should  be  as  nearly  round  or  square  as  the 
size  of  the  walls  and  jamb  will  permit.  The  circle  is  the  best  form, 
because  it  gives  the  greatest  area  in  proportion  to  the  perimeter,  or 
surface-producing  friction,  and  the  square  is  next.  If  the  flue  be  rec- 
tangular in  shape,  with  one  diameter  of  not  more  than  4  inches,  the 


142  CHIMNEYS. 

friction  will  be  great,  and  if  such  a  flue  be  so  placed  in  a  wall  that  one 
of  its  long  sides  is  parallel  to  a  surface  of  the  wall  which  is  exposed  to 
cold  air,  there  will  be  great  loss  of  heat. 

If  we  consider  chimney  flues  as  intended  only  to  carry  off  the 
products  of  combustion,  without  reference  to  questions  of  ventilation, 
the  following  are  the  sizes  which  give  the  best  results:  For  ordinary 
dwelling  houses  the  flue  for  each  room,  if  built  of  brick  in  the  usual 
way,  should  be  about  i  foot  square,  or  for  common  bedrooms 
9"x  12".  If  the  flues  be  lined  with  smooth  pipes  of  pottery  or  cement 
they  may  be  Q  inches  in  diameter. 

The  sizes  of  chimney  flues  used  in  ordinary  dwellings  vary  in 
different  parts  of  the  country.  In  Boston,  New  York  and  Chicago 
such  flues  are  usually  8"x  8"  or  8"x  12".  In  Baltimore  the  flues  are 
usually  i3"x  13".  In  New  Orleans  the  common  size  is  9/7x  9". 

This  difference  depends  in  part  upon  variations  in  size  of  brick  in 
common  use,  in  part  upon  the  more  general  use  of  closed  iron  stoves 
in  the  North,  and  in  part  to  traditions  of  masons  and  builders,  of  which 
it  would  be  very  difficult  to  trace  the  origin.  Tredgold's  rule  for 
chimneys  for  steam  boilers  is  as  follows:  "  The  area  of  a  chimney  in 
inches  for  a  low-pressure  steam  engine,  when  above  10  horse-power, 
should  be  112  times  the  horse-power  of  the  engine,  divided  by  the 
square  root  of  the  height  of  the'  chimney  in  feet.  Example:  Required 
the  area  of  a  chimney  flue  for  an  engine  of  40  horse-power,  the  height 
of  the  flue  being  70  feet. 

"  In  this  case  40  x  112 

--       --  =  533-2 


square  inches.  The  square  root  of  this  is  23  inches,  which  will  be  the 
side  of  a  square  chimney.  Or,  multiply  533  by  1.27  and  extract  the 
square  root  for  the  diameter  of  a  circular  one." 

In  another  place,  however,  Mr.  Tredgold  advises  that  chimneys 
be  built  double  the  size  called  for  by  this  rule.  Mr.  Milne  substitutes 
280  for  112  in  the  above  formula,  and  thus  obtains  results  between 
two  and  three  times  as  great.  Milne's  rule  is  as  follows:  The  square 
root  of  the  height  of  the  chimney  in  feet  multiplied  by  the  square  of 
its  internal  diameter  at  the  top  or  narrowest  part  in  feet  is  equal  to 
twice  the  horse-power  of  the  proper  boiler  for  the  chimney. 

By  horse-power  in  this  connection  is  meant  the  evaporation  of  a 
certain  amount  of  water  —  the  usual  estimate  being  that  a  cubic  foot  of 
water  at  60  degrees  evaporated  to  steam  is  equal  to  one  nominal  horse- 
power, which,  in  round  numbers,  would  require  70,000  thermal  units. 


CHIMNEYS.  143 

The  judges  at  the  Centennial  defined  a  horse-power  to  be  equal 
to  the  evaporation  of  30  pounds  of  water  from  a  temperature  of  212  de- 
grees. As  a  cubic  foot  of  water  weighs  a  little  over  62  pounds,  this 
standard  requires  less  than  half  the  fuel  which  would  be  needed  for  the 
former  —  being  only  about  29,000  thermal  units.  Taking  the  older  and 
more  usual  estimates  used  by  Tredgold,  allowing  eight  pounds  of  coal 
per  hour  per  horse-power  and  300  cubic  feet  of  air  for  the  combustion  of 
each  pound  of  coal,  we  find  that  we  shall  have  for  a  40  horse-power 
boiler  about  30  cubic  feet  of  gases  per  second  to  dispose  of.  If  we 
allow  a  velocity  of  5  feet  per  second  in  the  flue  we  shall  want  a  flue 
having  an  area  of  6  square  feet,  which  result  is  intermediate  between 
those  of  Tredgold  and  Milne,  and  is  probably  more  nearly  correct  than 
either. 

Another  rule  is  that  of  Murray  —  18  square  inches  for  12  pounds  of 
coal  per  hour. 

Another  rough-and-ready  rule  for  chimneys  for  the  ordinary 
horizontal  flue  boilers  is,  that  the  chimney  should  be  from  60  to  80  feet 
high,  and  have  an  area  equal  to  half  the  square  of  the  diameter  of  one 
of  the  tubes  multiplied  by  the  number  of  tubes.  In  such  a  boiler  15 
feet  of  boiler  surface  is  taken  as  equal  to  one  horse-power.  Still 
another  rule-of-thumb  is  that  the  size  of  the  flue  should  be  equal  to  the 
area  of  the  tubes. 

The  following  are  the  formulae  of  the  Babcock  &  Wilcox  Co.,  of 
New  York,  for  chimneys,  allowing  five  pounds  of  coal  per  hour  per  horse- 
power, and  taking  friction  as  equal  to  a  layer  of  air  2  inches  thick  over 
the  interior  surface: 

A  =  area  in  square  feet. 
E  =  effective  area. 
H  —  horse-power. 
h  =  height  of  chimney  in  feet. 


E  =  -  A  -  0.6 

Vh 


=  3-33 


For  a  27  horse-power  boiler  E  will  be: 

For  a  chimney  25  feet  high  ..........................  i  .62  square  feet 

36     "      "      ..........................  1-35 

49     "      "      .........................  1.  16 

"  "        64    "      "       ..........................  i.  01 


144 


CHIMNEYS. 


The  following  table  is  given   by  Prof.  W.  P.  Trowbridge  in   his 
book,  "  Heat  as  a  Source  of  Power:" 

TABLE  SHOWING  HEIGHTS  OF  CHIMNEYS  FOR  PRODUCING  CERTAIN   RATES   OF 
COMBUSTION  PER  SQUARE  FOOT  OF  AREA  OF  SECTION  OF  THE  CHIMNEY. 


Heights  in  Feet. 

Pounds  of  Coal 
Burned  Per  Hour 
Per  Square  Foot 
of  Section  of 
Chimney. 

Pounds  of  Coal  Burned 
Per  Hour  Per  Square  Foot 
of  Grate,  the  Ratio.of 
Grate  to  Section  of 
Chimney  Being  8  to  i. 

60 

7.5 

68 

8.5 

?6 

9-5 

•JC.                         .   . 

84 

10.5 

93 

11.  6 

99 

12.4 

CQ 

105 

13.  i 

5U  
cc    

til 

13-8 

60                          .                 

116 

14.5 

fa 

121 

15.1 

126 

15.8 

TC 

I3l 

16.4 

8p      

135 

16.9 

85. 

139 

J7-4 

qo.                                       ...          .... 

144 

18.0 

QC 

148 

18.5 

IOO 

152 

19.0 

105  

156 

19.5 

no 

1  60 

20.0 

In  this  connection  it  may  perhaps  be  well  to  say  a  word  about 
smoky  chimneys,  although  in  this  country  we  are  not  troubled  with 
them  to  anything  like  the  extent  that  they  are  in  England,  judging  from 
the  amount  of  English  literature  on  that  subject.  This  is  due  to 
the  fact  that  we  do  not  use  open  fireplaces  nearly  so  much  as 
they  do  in  England,  and  that  we  have  a  much  drier  climate.  In  some 
of  our  public  buildings  where  open  grates  are  used  there  has  been 
trouble  from  smoke,  and  a  very  amusing  account  is  given  of  the  efforts 
made  to  cure  it  in  one  of  the  large  public  buildings  in  Washington,  in 
which  there  was  a  series  of  rooms  freely  communicating  with  each 
other,  and  each  having  an  open  grate.  When  the  watchman  began  to 
build  the  fires  in  the  morning  he  found  the  first  one  had  a  magnificent 
draught,  the  second  one  not  so  good,  the  third  very  dubious  indeed, 
and  the  fourth  smoked  furiously.  Then  came  the  chimney  doctor 
with  a  patent  chimney  top,  which  was  placed  on  flue  No.  4,  lengthen- 
ing it  about  3  feet.  No.  4  now  drew  well,  but  No.  3  was  no  longer 
dubious,  for  it  smoked  like  a  tar  kiln.  Of  course  the  same  ^remedy  was 


CHIMNEYS..  145 

applied  to  No.  3,  but  then  Nos.  i  and  2  became  a  nuisance.  When 
these  also  had  been  duly  finished  with  the  patent  chimney  tops,  all  the 
flues  were  again  of  the  same  height,  and  the  process  had  to  be  begun 
de  novo.  The  true  remedy  in  such  a  case  is  to  see  that  each  chimney 
has  its  own  sufficient  supply  of  air  from  without,  and  does  not  draw 
against  another  flue. 

A  damp  flue  is  another  cause  of  smoky  chimneys,  since  the  current 
of  ascending  air  is  rapidly  cooled  by  evaporation.  This  often  adds 
greatly  to  the  difficulty  of  keeping  a  smoke  flue  situated  in  an  outer  wall 
in  good  working  condition. 

The  effects  of  wind  on  the  action  of  chimneys  will  be  considered 
hereafter. 

With  an  atmospheric  pressure  equal  to  29.92  inches  of  mercury, 
and  at  the  temperature  of  52°  F.  i  cubic  foot  of  dry  air  weighs  .0776 
pounds;  that  is,  13  cubic  feet  of  air  weigh  about  one  pound.  The 
specific  heat  of  air,  with  constant  pressure  is  0.2379;  tnat  is,  one  pound 
of  air  will  be  raised  i  degree  in  temperature  by  that  fraction  of  a 
thermal  unit",  or  one  thermal  unit  will  raise  the  temperature  of  one 
pound  of  air  4.2°  F.  If  we  assume  that  one  pound  of  coal  as  usually 
burned,  produces  8,000  available  units  of  heat,  it  will  heat  8,000 
pounds  =  104,000  cubic  feet  of  air,  4.2°  F.,  or  it  will  lift  this  same 
weight  of  air  772  feet.  In  heating  air  at  constant  pressure  a  certain 
amount  of  heat  disappears  in  producing  expansion  of  air,  and  this  ex- 
pansion gives  buovancy  or  ascensional  force  which  may  be  used  to 
secure  ventilation.  But  in  doing  this  the  air  passing  off  carries  off 
heat  with  it,  and  that  heat  is  no  longer  available  for  warmth — a  fresh 
amount  must  be  supplied  to  the  air  which  enters  to  take  its  place. 
The  more  we  ventilate  an  inhabited  room  in  cold  weather,  the  more 
heat  we  must  supply,  and  therefore  the  more  fuel  we  must  burn.  We 
may  do  much  to  secure  complete  combustion  of  our  fuel,  and  to  prevent 
waste  of  heat,  but  we  can  only  get  100  per  cent,  of  effect,  and  by  no 
form  of  apparatus  is  it  possible  to  effect  the  heating  of  a  well  ventilated 
room  with  the  amount  of  fuel  that  would  heat  the  same  room  if  the 
change  of  air  were  only  sufficient  for  heating  purposes. 

We  often  find  inventors  claiming  that  their  special  appliances  will 
give  both  ample  heat  and  abundant  ventilation  with  diminished  con- 
sumption of  coal,  but  there  is  little  use  in  wasting  time  over  the  ex- 
amination of  plans  or  proposals  for  contracts  in  which  this  claim  is' 
made. 

To  completely  burn  one  pound  of  coal  requires  about  295  cubic 
feet  of  air,  and  all  the  nitrogen,  oxygen,  carbonic  acid,  and  vapor  of 


146  BOTTLE    VENTILATION. 

water  in  this  air  must  be  heated,  and  will  therefore  absorb  and   carry 
off  some  of  the  thermal  units.     Whatever  may  be  the  methods  of  ven- 
tilation employed,  there  is  but  one  mode  of  getting  rid  of  the  products  ' 
of  combustion  of  fuel  that  need  be  mentioned  here,  and  that  is  by 
using  the  force  due  to  the  expansion  of  gases  by  heat. 

The  force  with  which  the  gases  from  the  burning  fuel  tend  to  rise 
in  a  chimney  may  be,  under  ordinary  circumstances,  measured  by  the 
temperature  at  which  these  gases  enter  the  flue.  The  lower  this  tem- 
perature, the  more  economical  the  apparatus,  so  far  as  heating  is  con- 
cerned. From  an  ordinary  steam  boiler  the  products  of  combustion 
enter  the  chimney  at  a  temperature  of  550°  F. 

From  a  good  hot-water  boiler,  properly  fired,  these  products  of 
combustion  enter  the  chimney  at  about  300°  F.,  the  temperature  of  the 
water  in  the  boiler  being  160°  F.,  while  from  a  so-called  air-tight  stove, 
with  a  large  amount  of  pipe,  they  may  pass  into  the  chimney  at  150°, 
or  even  so  low  as  IOOQ  F. 

These  are  merely  average  figures.  By  special  arrangements  it  is 
possible  to  cause  the  gases  from  the  furnace  of  a  steam  boiler  to  enter 
the  chimney  at  a  much  lower  temperature,  even  as  low  as  from  a 
stove  ;  but  such  arrangements  are  seldom  used,  since  with  coal  at 
present  prices  it  seems  cheaper,  on  the  whole,  to  use  the  usual  forms 
of  apparatus. 

Heated  air  in  a  bottle  having  a  narrow,  open  mouth,  will  not  rise, 
because  the  colder  air  around  cannot  enter  to  force  it  out  ;  but  if  the 
mouth  be  divided  by  a  partition  a  current  will  soon  be  established,  the 
cold  air  flowing  down  on  one  side  and  the  warm  air  streaming  up 
the  other.  This  is  commonly  illustrated  by  those  advocating  the  use 
of  a  patent  ventilator  which  depends  on  this  principle,  by  an  experi- 
ment which  always  deeply  impresses  those  who  see  it  for  the  first  time, 
and  the  exhibition  of  which  has  sold  many  ventilators — and  pur- 
chasers. This  experiment  consists  in  placing  a  short  piece  of  lighted 
candle  in  the  bottom  of  the  bottle.  The  heat  of  the  flame  promptly 
sets  up  a  circulation  within  the  bottle,  which  continues  until  enough 
carbonic  acid  has  been  produced  to  extinguish  the  light.  If,  just  before 
the  light  goes  out,  a  partition  be  inserted  in  the  neck  of  the  bottle,  the 
effect  above  mentioned  will  be  produced  ;  the  smoke  will  be  seen 
streaming  out  on  one  side,  and  the  light  will  soon  burn  again  as 
brightly  as  ever.  For  ventilating  a  bottle,  or  a  place  which  is  under 
the  same  conditions  as  a  bottle,  this  is  a  very  good  method  ;  but  if  you 
ever  put  such  an  arrangement  into  a  house  you  will  find  that  when  cold 
weather  comes  it  will  be  carefully  closed.  On  the  other  hand,  warm  air 


ASPIRATING    FLUES.  147 

will  not  rise  through  a  small  opening  into  a  room  filled  with  cold  air 
unless  this  room  has  some  opening  by  which  some  of  its  contained  air 
will  escape.  Forgetfulness  or  ignorance  of  this  fact  sometimes  causes 
great  disappointment  to  the  amateur  furnace-setter,  who  cannot 
imagine  why  an  apparatus  will  not  heat  a  room  above  it  in  which  every 
aperture  has  been  closed  "  to  keep  in  the  heat."  The  quickest  way  to' 
heat  a  room  under  such  circumstances  is  to  open  the  window.  It  will 
be  found  useful  to  remember  the  bottle  and  the  demoralized  furnace- 
setter  when  a  client  complains  of  a  smoky  chimney. 

Forced  ventilation  by  heat  will  usually  be  effected  by  what  is  com- 
monly called  an  aspirating  or  ventilating  chimney,  which  is  a  shaft  or 
flue  so  constructed  that  the  air  in  it  can  be  heated  without  necessarily 
heating  the  room  or  rooms  from  which  it  is  desired  to  withdraw  the  air, 
so  that  no  discomfort  need  be  caused  by  its  use  in  warm  weather.  This 
heat  may  be  applied  by  means  of  an  open  grate  placed  in  the  shaft,  as 
is  done  in  the  aspirating  tower  for  the  House  of  Commons,  and  in  some 
mines,  or  by  means  of  a  stove,  heating  a  sheet-metal  pipe  passing  up 
the  chimney,  or  by  gas  jets,  or  hot-water  boilers,  or  by  the  circulation 
of  hot  water  or  steam  in  coils  of  pipes  or  radiators  suitably  arranged  in 
the  chimney,  and  known  as  accelerating  coils. 

The  open  grate  is  a  wasteful  and  troublesome  mode  of  applying 
heat  for  this  purpose,  and  should  only  be  employed  under  very  excep- 
tional circumstances. 

The  use  of  gas  jets  would  also  be  very  expensive  in  this  country 
if  the  amount  of  air  to  be  moved  is  large.  The  necessary  fixtures  for 
the  gas  heating  of  a  flue  can,  however,  often  be  introduced  in  old 
buildings  where  any  other  sort  of  apparatus  would  be  practically  out 
of  the  question,  as  they  take  up  very  little  space,  and  for  the  ventila- 
tion of  a  water  closet,  or  similar  purposes,  this  method  gives  fair  results 
at  small  cost.  But  while  the  use  of  gas  combustion  as  a  means  of  forc- 
ing ventilation  is,  for  economical  reasons,  not  to  be  recommended  if 
this  is  to  be  the  sole  purpose  for  which  the  gas  is  consumed,  it  should 
not  be  forgotten  that  the  burning  of  gas  for  illuminating  purposes  gives 
rise  to  heat  which  can  often  be  made  use  of  advantageously  for  pur- 
poses of  ventilation.  This  is  especially  the  case  in  theaters  and  other 
large  assembly  halls  which  are  used  at  night,  in  which  a  very  consider- 
able amount  of  aspirating  power  may  be  obtained  by  suitable  connec- 
tion of  tubes  and  flues  with  the  means  of  illumination. 

The  heating  of  the  aspirating  chimney  by  means  of  a  central  metal 
pipe  is  a  method  very  commonly  employed  to  utilize  the  waste  heat 
from  the  flues  of  steam  boilers,  etc.,  and  gives  very  excellent  results, 


148  ACCELERATING    COILS. 

as  may  be  seen  by  referring  to  those  obtained  in  the  Barnes  Hospital, 
described  in  a  subsequent  chapter.  In  private  houses  the  kitchen 
chimney  is  sometimes  used  in  this  way  as  a  ventilating  shaft  for  the 
whole  or  a  part  of  the  house,  the  pipe  from  the  stove  or  range  being 
carried  up  through  the  center  of  the  chimney  flue. 

The  application  of  steam  heat  for  the  purpose  of  accelerating  the 
movement  of  air  in  ventilating  flues  is  often  a  very  convenient  and  sat- 
isfactory method  where  this  source  of  power  is  available  ;  but  the 
amount  of  heating  surface  allowed  for  this  purpose  by  many  heating 
engineers  is  very  insufficient  for  the  purpose,  and  the  coils  are  often 
wrongly  placed. 

Prof.  W.  P.  Trowbridge,  of  Columbia  College,  published  in 
1882,  in  the  School  of  Mines  Quarterly,  a  very  excellent  paper  on  the 
"  Determination  of  heating  surface  required  in  ventilating  flues,"  with 
special  reference  to  the  formulae  used  in  calculating  this  for  coils  of  steam 
pipe,  and  subsequently  gave  a  brief  article  on  the  same  subject  in  the 
Sanitary  Engineer,  which  is  so  clear  and  concise  that  it  is  here  quoted  : 

"  The  employment  of  steam  pipes  at  the  bases  of  ventilating  flues 
seems  to  me  to  be  worthy  of  more  extended  application  than  has  here- 
tofore been  accorded  to  this  method  of  promoting  activity  of  circula- 
tion of  air  for  the  purposes  of  ventilation.  It  is  only  applicable,  of 
course,  for  buildings  heated  by  steam;  but  of  buildings  thus  heated,  a 
few  cnly,  such  as  hospitals,  asylums,  theaters,  and  other  public  build- 
ings, are  of  sufficient  magnitude,  or  are  occupied  by  such  numbers  as 
to  warrant  the  use  of  fans  or  blowers. 

"  Ordinary  architectural  structures  must  have  appliances  for  ven- 
tilation which  demand  the  least  possible  attention  ;  or,  perhaps,  no 
attention  whatever,  except  the  opening  or  closing  of  registers.  And 
yet  it  is  well  known  that  when  under  these  circumstances  spontaneous 
or  natural  ventilation  is  depended  on,  there  are  occasions  and  circum- 
stances when  partial  or  complete  stagnation  of  air  is  inevitable.  In 
buildings  heated  by  steam  the  remedy  is  simple  and  effective.  Steam, 
or  even  hot-water  pipes  properly  arranged  at  the  base  of  any  vertical 
flue  will  furnish  the  necessary  heat  to  produce  a  draught.  The  simple 
question  involved  is  the  area  of  heating  surface  demanded  for  a  given 
vertical  flue,  and  for  a  given  quantity  of  air  to  be  discharged  per  hour. 

"In  a  paper  first  published  in  the  School  of  Mines  Quarterly  (the 
abstract  results  of  which  were  printed  afterward  in  the  Sanitary  Engi- 
neer], I  discussed  the  question  and  deduced  a  simple  formula  for  the 
heating  surface.  I  now  venture  to  refer  to  that  formula,  and  show  how 
it  may  be  used  with  the  least  amount  of  arithmetical  calculations. 


ACCELERATING    COILS.  149 


The  formula  is  as  follows  : 

W  T 


"  In  this  formula  (S)  represents  the  number  of  square  feet  in  the 
exterior  surface  of  the  coil  or  cluster  of  steam  pipes  at  the  base  of  the 
flue  ;  (Ta)  is  the  absolute  temperature  of  the  external  air  —  that  is,  the 
common  or  thermometric  temperature  -(-  459.4°  (or  /°  -j-  459.4°). 

"  (  W)  represents  the  weight  of  air  in  pounds  which  is  discharged 
in  one  second. 

"  (H)  represents  the  height  of  the  flue,  and  (Ts)  is  the  absolute 
temperature  of  the  steam  in  the  coil  (/'.  e.,  ts  -+-  459-4°)- 

"The  constant  1,500  is  derived  from  certain  constants  which  were 
employed  in  deducing  the  formula,  one  of  which  was  the  force  of 
gravity,  another  the  specific  heat  of  air,  another  the  rate  of  transfer  of 
heat  to  air  by  coils,  from  Mr.  C.  B.  Richard's  experiments,  and  another 
the  ratio  between  the  theoretical  velocity  and  the  actual  velocity  in  the 
flue,  as  influenced  by  friction.  For  ordinary  and  the  most  favorable 
circumstances  the  actual  velocity  in  the  flue  is  best  if  it  be  established 
at  about  5  feet  per  second,  and  it  is  for  this  actual  velocity  that  the 
formula  in  its  simplified  form  as  above  is  adopted. 

"  Another  formula,  well  known,  and  which  is  needed,  is  that  for 
the  weight  of  air  discharged  per  second  —  to-wit  : 

W  =  A  X  Dc  X  V, 

"That  is,  the  weight  discharged  is  found  by  multiplying  the  cross- 
section  of  the  flue  (A)  by  the  velocity  (V)  and  the  density  (JDC)  of  the 
air  in  the  flue. 

"  By  the  calculations  in  my  original  paper,  I  found  that  the  density 
in  the  flue  which  will  result  from  the  proportions  given  by  this  formula, 
will  be  o  0719  pounds  per  cubic  foot.  Hence  the  area  of  flue  for  a 
given  discharge,  W,  will  be  : 

W  W  W 

-  Dc  V    ~  0.0719  X  5  ==   -3595 

or,  A  •=.  3  W  approximately. 

"  That  is,  the  cross-section  of  the  flue  in  square  feet  should  be 
three  times  the  weight  of  air  discharged  per  second. 

"  An  example  will  show  the  method  of  using  these  formulas  for  all 
ordinary  cases. 

"  Suppose  the  air  of  a  room  3o'x4o'  and  15  feet  from  floor  to 
ceiling  is  to  be  renewed  four  times  every  hour. 


150  ACCELERATING    COILS. 

"  The  cubic  contents  are  3o'X4o'Xi5'  =  18,000  cubic  feet.  At 
the  ordinary  temperature  and  pressure,  this  air  will  weigh  about  Tf  F  of 
a  pound  per  cubic  foot,  and  the  weight  of  air  discharged  per  hour  will 
be  4X  18,000  x  .08  =  5,760  pounds,  or  1.6  pounds  per  second. 

"The  required  area  or  cross-section  will  be  A  =  3.x  1.6  —4. 8 
square  feet.  If,  now,  we  suppose  the  steam  in  the  coil  to  be  low- 
pressure  steam,  for  instance  five  pounds  above  the  atmosphere,  we 
shall  have  for  its  temperature,  F.  228°,  and  if  we  assume  the  exterior 
temperature  of  the  air  to  be  60  degrees,  we  shall  have  conditions  which 
will  apply  to  spring  or  autumn  weather,  and  the  same  arrangements 
then  determined  will  give  better  results  in  winter  or  cooler  weather  ; 
with  these  assumptions  we  have  : 

c  _          1500  X  1.6  (60  +  459-4) 
~  H  (228°  +  459.4  -~6o  +  459.4) 

moo  x  1.6  (60  +  459.4)  _  4-9 
or'  H  (228*  -  6ou)  "  H ~]     15°°' 

"  If  the  flue  is  50  feet  high,  we  shall  have  : 

1500  x  4.9 
S  = — =  30  X  4.9  =  J47  square  feet. 

"  Hence,  the  conditions  of  ventilation  assumed  will  require  an  ag- 
gregate area  of  ventilating  flue  of  4-^  square  feet  in  cross-section,  and 
147  square  feet  of  heating  surface  in  the  coil  or  cluster  of  pipes  at  the 
base. 

"If  more  than  one  flue  is  employed,  which  would  probably  be 
desirable,  in  order  to  have  a  better  distribution  of  the  inflowing  air 
(two  flues  for  instance),  then  each  would  have  an  area  of  2TS¥  square 
feet,  and  each  would  be  heated  at  the  base  by  pipes  having  73^  square 
feet  of  surface. 

"  It  may  be  thought  that  this  amount  of  surface  is  excessive  for 
the  degree  or  ventilation  assumed. 

"The  reply  to  this  objection  is,  that  if  any  one  expects  to  obtain 
full  and  sufficient  ventilation  without  expending  an  appropriate  amount 
of  money,  both  for  fixtures  and  for  fuel,  such  a  one  is  mistaken. 

"  It  might  as  well  be  expected  to  get  water  from  a  well  without 
means  for  drawing  or  pumping  it.  The  size  of  the  bucket  or  pump, 
and  the  power  applied,  will  determine  the  exact  amount  of  water  ob- 
tained per  hour,  and  the  cost  of  obtaining  it. 

"  The  sooner  this  law  is  universally  recognized  for  ventilation,  the 
sooner  will  ventilation  arrangements  be  generally  successful. 


ACCELERATING    COILS.  151 

u  It  should  be  further  remarked  as  of  great  importance  in  arrang- 
ing steam  pipes  for  heating  air  in  its  passage  to  flues,  that  the  pipes 
should  not  block  up  the  flues,  but  should  be  placed  in  an  enlargement 
or  chamber,  so  that  the  aggregate  area  through  and  among  the  pipes 
shall  be  equal  to  the  area  of  the  flue,  or  even  10  per  cent,  greater. 
Moreover,  the  pipes  or  heaters  should  be  so  arranged  that  no  air  will 
pass  without  coming  in  contact  with  the  heated  surfaces.  A  baffled 
passage,  causing  the  filaments  of  air  to  assume  a  tortuous  course 
among  the  pipes,  is  the  proper  one.  If  the  above  conditions  are  ful- 
filled and  properly  applied,  there  seems  hardly  any  limit  to  which  ven- 
tilation may  be  carried  in  steam-heated  buildings." 

An  interesting  account  of  the  application  of  steam  coils  to  produce 
a  ventilating  current  is  given  in  a  description  of  the  heating  and  ven- 
tilation of  the  library  building  of  Columbia  College,  New  York,  con- 
tained in  the  Sanitary  Engineer,  of  June  28,  1883,  from  which  is  taken, 
by  permission,  the  following  account  and  illustration  : 

The  ventilation  was  arranged  by  the  architect,  Mr.  Haight,  in  ac- 
cordance with  the  suggestions  of  Professor  Trowbridge. 

The  system  of  heating  is  by  indirect  radiation  from  surfaces 
heated  by  low-pressure  steam.  The  radiators  are  arranged  as  shown 
in  Fig.  7. 

In  two  of  the  large  lecture  rooms  steam  coils  are  placed  at  the 
base  of  the  exhaust  flues  to  induce  an  upward  draught.  "  In  each  room 
there  are  four  fresh-air  inlets,  each  measuring  i2"x2o",  or  equivalent 
dimensions,  less  the  obstructions  of  the  register.  The  steam  coils  in 
these  four  inlets  have  a  combined  heating  surface  of  720  square  feet. 
In  one  room  all  four  hot-air  registers  are  near  the  ceiling  (10  feet  from 
the  floor  to  the  bottom  of  the  register ;  the  room  is  15  feet  high), 
but  in  the  other  room  three  of  them  are  near  the  floor.  The  latter 
have  sheet-iron  screens  in  front  of  them,  8  inches  larger  than  the 
register,  and  the  same  distance  from  the  wall,  to  protect  persons  sitting 
in  front  of  the  register  from  the  direct  current.  They  are  turned  back 
to  the  wall  on  the  end  toward  the  exhaust  flues,  to  direct  the  current 
away  from  the  latter." 

The  outlets  in  both  rooms  are  at  the  outside  corners,  at  the  floor 
level,  into  large- circular  flues  in  the  corner  turrets.  The  accompany- 
ing plan  and  section,  Figs.  8  and  9  make  clear  the  location  and 
size  of  the  heating  coils  and  the  air  passage  through  and  around  them. 

The  full  size  of  the  main  outlet  from  the  room  into  each  turret  is 
about  32"x38/r.  This  may  be  reduced  as  desired  by  a  common  register 
valve,  which,  however,  is  kept  locked  and  under  the  control  of  the 


ACCELERATING    COILS. 


FIG.  6.— PLAN  OP  LECTURE  ROOM,  SHOWING  VENTILATING  SYSTEM. 


ACCELERATING    COILS. 


153 


np 

FIG.  7.-SECTION  THROUGH  COIL  BOX  IN  CELLAR. 


154  ACCELERATING    CQILS. 

janitor.  The  arrangement  of  these  coils  was  designed  by  Professor 
Trowbridge.  They  consist  of  three  stacks  of  vertical  i-inch  pipes,  ar- 
ranged in  quincunx  order  on  bases  i'x22/r,  and  about  5  feet  high. 
The  rows  perpendicular  to  the  register  are  separated  by  sheets  of  tin, 
designed  to  serve  as  secondary  radiating  surfaces,  thus  largely  increas- 
ing the  efficiency  of  the  coils.  Horizontal  sheets  also  are  fitted  over 
the  pipes  at  intervals  of  i  foot.  The  pipes  fill  the  lower  back  part 
of  the  passage  into  the  flue,  but  a  considerable  unoccupied  portion 
remains  above  and  in  front  of  them,  as  shown  by  the  plan,  and  section 
perpendicular  to  the  register.  The  floor  between  the  coils  and  register 
is  tiled;  the  register  is  fastened  only  by  a  few  screws,  so  that  it  may  be 
easily  removed  to  clean  out  the  dust  in  front  of  and  among  the  coils. 


FIG.  8. -PLAN  OF  COIL  AND  EXHAUST   SHAFT   IN  CORNER  TURRET. 

The  total  heating  surface  of  the  three  stacks  of  pipe  in  each  corner 
outlet  is  650  square  feet.  The  steam  supplied  to  these  pipes  is  not 
from  the  low-pressure  system  (the  maximum  pressure  of  which  is  10 
pounds),  bat  has  a  maximum  pressure  of  50  pounds. 

The  smaller  circle  in  the  turret  (Fig.  8),  indicates  the  size  of 
the  flue  up  to  this  (the  first)  story,  when  it  is  increased  to  the  size  indi- 
cated by  the  larger  circle.  Above  the  larger  outlet  at  the  bottom  is  a 
smaller  one  directly  above  (10  feet  above  the  floor),  into  the  same 


FANS    AND    BLOWERS. 


155 


large  flue,  designed  as  an  auxiliary  outlet  for  a  natural  circulation.  By 
these  means  it  is  calculated  that  the  air  in  the  rooms  may  be  changed 
every  15  minutes. 

Extensive  use  of  steam  coils  in  aspirating  flues  is  also  made  in  the 
Johns  Hopkins  Hospital,  in  Baltimore.  In  this  case  a  certain  part  of 
the  efficiency  of  some  of  the  steam  coils  is  lost,  owing  to  the  fact  that 
they  are  placed  high  in  the  shafts  above  the  entrance  into  the  shafts  of 
the  upper  air  ducts,  which  are  the  ones  which  will  do  most  of  the  work 
in  warm  weather.  This  loss  might  have  been  avoided  by  bringing 
these  flues  down  to  the  base  of  the  aspirating  chimney,  at  which  point 
the  accelerating  coils  might  then  have  been  placed,  with  the  result  of 
obtaining  a  longer  column  of  heated  and  rarified  air,  and  acorrespond- 


FIG  9.— SECTION  THROUGH  a  b. 

ing  increase  of  power.  To  do  this,  however,  would  have  increased  the 
cost  of  construction  to  such  an  extent  that  it  was  thought  better  to 
accept  th*2  slightly  increased  cost  of  running  the  present  apparatus  for 
the  few  days  during  which  it  will  be  required. 

The  use  of  some  form  of  fan  or  blower  is  a  favorite  method 
with  engineers  for  producing  currents  of  air  for  purposes  of  ventila- 
tion or  of  heating.  They  have  been  used  for  this  purpose  in  mines 
for  over  400  years,  and,  while  engineers  differ  as  to  their  relative 
economy  and  utility  for  this  purpose  as  compared  with  the  direct  ap- 
plication of  heat  in  one  or  more  of  the  vertical  shafts  of  the  mine, 
which  is  thus  converted  into  a  chimney,  the  tendency  for  the  last 


156  FANS    AND    BLOWERS. 

30  years  has  been  decidedly  towards  increased  use  of  fans  for  ventila- 
tion of  mines,  and  some  very  large  ones  have  been  put  in  place  for 
this  purpose. 

Heating  engineers  also  often  wish  to  use  the  mechanical  power  of 
a  fan  or  blower  to  force  the  air  to  be  supplied  over  a  centralized  collec- 
tion of  radiating  surface,  thus  saving  the  cost  of  long  mains  and 
returns,  and,  in  the  case  of  large  buildings,  enabling  them  to  cheapen 
the  cost  of  the  plant.  A  lower  bid  for  heating  and  ventilating  apparatus 
does  not,  however,  prove  that  the  system  is  a  cheaper  one.  If  power  is 
not  employed  for  any  other  purpose,  so  that  machinery  must  be 
specially  provided  to  run  the  fan  and  the  cost  of  attendance  charged  to 
it,  it  may  be  very  expensive. 

The  use  of  forced  ventilation  fey  means  of  a  fan  or  blower  is 
especially  useful  in  theaters,  churches  and  assembly  halls  where  large 
numbers  of  people  are  to  be  gathered  for  a  comparatively  short  time, 
in  workshops  and  factories  of  certain  kinds  for  the  removal  of  dusts 
and  vapors,  in  tunnels  and  in  mines,  especially  in  coal  mines  ;  and  in 
large  hospitals  and  asylums,  not  so  much  for  continuous  use  as  to  pro- 
vide the  means  of  flushing  out  the  wards  with  air,  and  of  securing  the 
movement  of  air  required  at  those  times  when  the  external  air  is  but  a 
few  degrees  below  70°  F.,  and  when,  consequently,  the  aspiration  power 
of  chimneys  is  much  diminished. 

As  applied  to  theaters  and  halls  of  assembly,  the  fan  is  usually 
employed  for  forcing  air  into  the  room  on  what  is  called  the  plenum 
system,  and  illustrations  of  its  application  in  this  way  will  be  found  in 
the  descriptions  of  the  Hall  of  the  House  of  Representatives  in  Wash- 
ington, of  the  School  of  the  Sorbonne  in  Paris,  and  of  the  Vienna, 
Frankfort,  and  New  York  opera  houses,  and  of  other  buildings  the 
plans  of  which  are  given  in  subsequent  chapters. 

The  use  of  an  aspirating  fan  in  such  rooms  or  buildings  is  not, 
as  a  rule,  desirable. 

For  buildings  which  are  constantly  occupied,  such  as  hospitals, 
asylums  and  prisons,  the  fan  is  an  useful  adjunct  to  provide  for  daily 
flushing  and  for  occasional  conditions  of  the  atmosphere  in  the  spring 
and  autumn,  but  it  is  not  desirable  to  so  arrange  it  that  its  working  is 
a  necessity  to  obtain  heat  or  change  of  air  in  cool  weather.  Fans 
are  kept  constantly  running  in  some  of  the  larger  insane  asylums  in 
this  country,  as,  for  example,  in  the  New  York  Asylum  at  Utica,  where 
two  fans,  each  12  feet  in  diameter,  are  employed  for  this  purpose.  The 
heating  surfaces  are,  however,  not  so  centralized  in  this  asylum  that 
the  stoppage  of  the  fans  would  cut  off  all  the  heat  from  the  wards. 


FANS    AND    BLOWERS.  157 

What  is  called  trie  central  hot-blast  method  of  heating  is  not  a 
desirable  one  for  buildings  of  this  kind. 

The  largest  fans  are  those  used  in  some  coal  mines.  There  is  one 
50  feet  in  diameter  at  the  St.  Hilda  Colliery,  South  Shields.  This  fan 
can  be  driven  at  a  speed  of  50  revolutions  per  minute,  at  which 
rate  it  is  estimated  to  move  200,000  cubic  feet  of  air  per  minute. 
The  use  of  fans  in  this  connection  will  be  referred  to  hereafter  in 
speaking  of  mine  ventilation. 

A  very  important  use  of  small  aspirating  fans  is  to  remove  dusts, 
or  offensive  or  dangerous  gases  or  vapors,  produced  in  various  pro- 
cesses of  manufacture,  by  drawing  them  off  through  hoods  placed 
close  to  the  machines  or  vessels  in  which  they  are  produced,  so  that 
such  dusts  or  fumes  are  not  allowed  to  escape  into  and  contaminate  the 
general  air  supply  of  the  room.  In  this  way  many  trades  which  would 
otherwise  be  disagreeable  or  dangerous  to  health  may  be  so  conducted 
as  to  be  harmless,  and  the  applications  of  this  method  are  manifold. 

When  it  becomes  necessary  to  devise  a  plan  of  ventilation  for  a 
building  already  constructed  in  which  it  is  difficult  or  impossible  to 
provide  aspirating  flues  and  chimneys  of  sufficient  size  to  act  as  outlets, 
and  especially  where  steam  or  electric  power  is  available,  the  use  of 
one  or  more  comparatively  small  aspirating  fans  placed  in  the  ceiling, 
or  in  the  upper  half  of  a  window,  will  often  give  very  good  results. 
In  making  such  an  application  of  the  fan  care  should  be  taken  to  pro- 
vide sufficient  and  properly  distributed  fresh-air  inlets.  This  is  a 
matter  which  seldom  receives  attention  from  the  vendors  of  patent 
fans — who  have  often  set  them  up  without  the  slightest  attempt  to  pro- 
vide a  fresh-air  supply.  Even  more  absurd  than  this  is  the  supposition 
that  ventilation  is  effected  by  placing  small  fans  run  by  electro-motors 
in  a  room  without  providing  any  outlet,  the  effect  being,  of  course, 
merely  a  stirring  up  of  the  air  without  effecting  any  removal  or  change. 
The  noise  made  by  fans  or  blowers  becomes  an  important  matter  to  be 
taken  into  account  in  selecting  one  to  be  used  for  the  ventilation  of  a 
building.  To  move  a  given  quantity  of  air  the  smaller  the  fan  the 
greater  must  be  its  velocity,  and  the  greater  the  velocity  the  greater 
the  liability  to  produce  an  unpleasant  amount  of  noise.  The  various 
modifications  in  the  form  of  the  case  and  blades  of  fans  which  have 
been  and  are  the  subject  of  patents,  have  comparatively  little  effect 
on  the  actual  efficiency  of  the  instrument,  but  may  have  considerable 
on  the  noise  produced.  For  fans  intended  to  deliver  a  large  amount 
of  air  against  comparatively  low  pressures,  not  exceeding  that  of  i 
or  2  inches  of  water,  comparatively  large  fans  run  at  low  speed  and 


158 


FANS    AND    BLOWERS. 


nearly  noiseless,  appear  to  give  satisfactory  results.  This  is  the  sort 
of  fan  used  in  the  House  of  Representatives  at  Washington,  and  in  the 
Barnes  Hospital,  and  is  described  and  illustrated  in  a  paper  "  On  the 
conditions  and  the  limits  which  govern  the  proportions  of  rotary  fans," 
by  Mr.  Robert  Briggs,  published  as  an  excerpt  from  the  Minutes  of 
Proceedings  of  the  Institution  of  Civil  Engineers,  Volume  XXX., 
Session  1869-70,  Part  n. 

The  proper  proportioning  of  the  ducts  on  each  side  of  such  a  fan 
to  the  diameter  of  the  fan  itself  is  essential  to  obtain  the  best  results, 
and  changes  in  the  size  of  such  ducts,  where  the  supply  of  air  is  to 
remain  constant,  must  result  in  loss  of  efficiency. 

The  table  on  the  opposite  page  relates  to  rotary  fans  of  compar- 
atively large  size  and  low  speed,  and  is  taken  from  the  paper Jiy  Mr. 
Robert  Briggs,  above  referred  to.  Such  fans  can  move  large  quan- 
tities of  air  economically,  but  at  low  pressure  only,  usually  not  exceeding 
that  of  i  or  2  inches  of  water. 

The  following  table  is  taken  from  a  recent  catalogue  of  the 
Buffalo  Forge  Company: 


Cubic  Feet 

Number 
of 
Blower 

Height  of 
Blower. 

Size  of  Outlet. 

Diameter  and 
Base  of 
Pulley. 

Ordinary 
Speed. 

Horse- 
Power 
Eng. 

of  Air  per 
Minute  Deliv- 
ered at  i  Ounce 
Pressure. 

48 

5  2-  inch 

16^x16^ 

lox  8 

690 

2.3 

8,740 

49 

60 

18     xi8 

ux  9 

623 

3-0 

11,000 

50 

70 

21  J^X2I  l/z 

12X10 

522 

4.0 

15.280 

50^ 

80 

24     X24 

I2XIO 

450 

5-4 

19,900 

51 

90 

27     X27 

14x10 

414 

6.7 

25.900 

52 

IOO 

30^x30^ 

16x12 

370 

8.4 

32  500 

53 

I  ID 

34     X34 

18x13 

323 

10.6 

39  300 

54 

120 

37^x37^ 

20x14 

296 

13.0 

49.i6i 

55 

130 

40^x40^ 

22X16 

275 

15    0 

57  720 

56 

150 

48^x48^ 

26x16 

224 

20.  o 

81,120 

For  combinations  of  these  blowers  with  a  heater  containing  steam 
pipe  forming  a  hot-blast  apparatus,  the  same  company  gives  a  table 
which  allows  the  following  amount  of  heating  surface  stated  in  square 
leet— viz.,  for  No.  50,  651;  for  No.  51,  869  ;  for  No.  52,  1,086  ;  53, 
r,521  ;  54,  i,955  ;  55,  2,39°  ;  and  for  56,  3,042  square  feet. 

As  it  will  usually  be  found  advisable  to  run  the  fan  at  about  75 
per  cent,  of  the  speed  indicated  in  the  column  headed  "  Ordinary 
Speed"  in  the  above  table,  and  as  the  amount  of  air  delivered  will  be 
diminished  by  this,  and  also  in  most  cases  by  friction,  it  is  not  safe  to 


FANS    AND    BLOWERS. 


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count  on  obtaining  much  more  than  half  the  amount  of  air  indicated 
in  the  last  column. 

If  we  take  No.  54,  a  lo-foot  blower,  with  an  outlet  of  about  9.9 
square  feet,  it  would  require  a  velocity  of  the  current  through  this  out- 
let of  82  feet  per  second  to  supply  the  49,161  cubic  feet  of  air  assigned 
as  the  capacity  of  this  blower. 

Such  a  velocity,  if  obtainable,  involves  great  loss  of  power  by  fric- 
tion. For  the  same  work  Mr.  Briggs'  table  would  allow  an  outlet 
of  about  60  square  feet,  giving  a  velocity  of  about  14  feet  per  second. 

The  use  of  the  force  contained  in  compressed  air  has  thus  far  not 
been  employed  especially  for  ventilation  purposes,  although  it  has  in- 
cidentally been  of  value  in  tunnel  construction  where  drills  or  cutters 
driven  by  compressed  air  have  been  employed,  since  the  air  escaping 
from  the  machines  working  at  the  face  of  the  rock  forces  backwards 
and  outwards  the  air  fouled  by  powder  smoke,  and  by  the  respiration 
of  the  workmen.  If,  hereafter,  it  shall  be  found  expedient  to  furnish 
from  a  central  point  compressed  air  as  a  means  of  rendering  stored  force 
available  at  distant  points,  it  would  be  quite  possible  to  use  it  in  the 
form  of  a  jet  to  induce  motion  in  a  comparatively  large  column  of  air. 
The  steam  jet  has  been  occasionally  used  in  this  way,  but  it  is  not  an 
economical  method  of  moving  considerable  quantities  of  air. 

A  small  stream  or  jet  of  falling  water  may  be  used  on  the  same 
principle  as  the  steam  jet  to  induce  movement  of  a  column  of  air.  An 
apparatus  on  this  principle  is  connected  with  the  lecture  room  of  Pet- 
tenkofer's  Laboratory  of  Hygiene  in  Munich.  It  consists  of  an  U- 
shaped  galvanized-iron  tube,  the  upper  extremity  of  one  arm  opening 
to  the  external  air,  and  the  upper  extremity  of  the  other  arm  opening 
into  the  hall.  A  water  pipe,  with  nozzle  pointing  downward,  enters 
each  branch  of  the  tube  near  the  top,  the  flow  being  controlled  by  stop- 
cocks outside  of  the  tube.  The  direction  of  the  current  of  air  in  the 
tube  depends  upon  which  stop-cock  is  opened,  so  that  it  will  either 
inject  air  into,  or  draw  it  from  the  hall.  A  small  pipe  at  the  bottom 
of  the  U  permits  the  fallen  water  to  run  off. 


CHAPTER  IX 

EXAMINATION    AND    TESTING    OF    VENTILATION. 

IF  we  wish  to  know  whether  a  room  or  building  is  sufficiently  and 
satisfactorily  ventilated,  and  if  not  so  ventilated,  the  cause  of  the 
deficiency,  we  must  ascertain  the  condition  of  the  air  contained  in  it  as 
regards  odor,  presence  of  suspended  matters,  and  of  gases  or  vapors 
not  found  in  perceptible  amounts  in  the  normal  atmosphere,  and 
especially  as  regards  the  proportions  of  carbonic  acid  and  moisture  con- 
tained in  it  as  compared  with  those  found  in  the  immediate  sources  of 
supply. 

The  carbonic  acid  test  is  the  one  chiefly  relied  upon  to  determine 
the  relative  amount  of  impurities  that  are  being  added  to  the  air,  and 
whether  the  distribution  of  the  fresh  air  is  such  as  to  ensure  its 
thorough  mixture  with  the  mass  of  the  air  within  the  room. 

But  we  also  need  to  know  the  amount  of  floor  space  and  cubic 
space  contained  in  the  room,  the  number  of  persons  in  it,  or  to  be  sup- 
plied, whether  its  occupation  is  temporary — that  is,  for  an  hour  or  two 
only,  or  permanent,  that  is,  for  six  hours  or  more  in  succession — the 
amount  of  fresh  air  introduced  per  hour,  and  the  position,  direction 
and  velocity  of  the  air  currents  produced  within  the  room,  and  their 
effect  upon  the  persons  occupying  it ;  and  it  will  often  happen  that 
these  data,  or  a  part  of  them,  are  the  only  ones  we  have  from  which  to 
judge,  seeing  that  the  chemical  tests  are  not  available. 

In  hospital  wards,  soldiers'  barracks,  or  in  dormitories  of  any  kind, 
as  in  common  lodging  rooms,  tenement  houses,  prison  cells,  etc.,  and 
in  school  rooms,  the  determination  of  the  number  of  square  feet  of 
floor  space,  and  of  cubic  feet  of  air  space  to  each  person  is  an  impor- 
tant item  in  forming  a  judgment  as  to  the  probable  sufficiency  of  the 
means  of  ventilation. 

Having  obtained  the  dimensions  of  the  room,  the  next  thing  is  to 
note  the  position  and  size  of  the  openings  in  the  room  which  are  either 
intended  to  serve,  or  which  may  serve,  as  inlets  and  as  outlets,  and  to 
determine  the  direction  and  rapidity  of  the  movement  of  the  air  through 
them.  If  there  are  distinct  and  special  outlets,  as  by  flues  provided 


162 


ANEMOMETERS. 


for  the  purpose,  it  may  be  sufficient  to  measure  the  amount  of  air  pass- 
ing through  these  outlets  or  flues,  since  the  amount  of  incoming  air 
must  be  nearly  or  quite  the  same.  The  quantity  of  air  passing  through 
a  given  opening  is  found  by  multiplying  the  area  of  the  opening  stated 
in  square  feet  or  fractions  of  a  foot  by  the  velocity  of  the  current 
stated  in  lineal  feet  per  minute,  the  product  being  the  number  of 
cubic  feet  of  air  passing  per  minute. 

The  velocity  of  the  air  current  is  determined  by  instruments  known 
as  anemometers,  pressure  gauges  or  manometers.  Those  which  indi- 
cate the  velocity  by  registration  of  the  pressure  exerted  are  some- 
times called  static  anemometers. 


FIG.  10. 


THE  DIAL. 


Dynamic  anemometers,  or  air  meters,  are  those  so  constructed 
that  the  velocity  of  the  air  current  can  be  determined  by  the  rate  at 
which  it  causes  a  very  light  propeller-like  wheel  placed  in  its  course  to 
revolve.  The  number  of  revolutions  of  this  wheel  are  recorded  in 
feet  or  meters  upon  a  dial  with  which  it  is  connected  by  an  arrange- 
ment of  cogs,  and  from  this  dial  the  rate  at  which  the  current  is  pass- 
ing over  the  instrument  can  be  read  in  a  few  minutes. 

For  the  study  of  ventilation  by  anemometric  methods,  the  dynamic 
forms  of  the  instrument  are  those  most  commonly  employed,  though 
for  certain  purposes,  as  will  be  explained  hereafter,  the  static  anemom- 
eters are  sometimes  used. 

Of  the  dynamic  anemometers,  a  variety  of  different  forms  exist, 
though  the  principles  involved  in  them  all  are,  in  the  main,  the  same. 


ANEMOMETERS. 


I63 


The  instrument  usually  employed  in  this  country  and  in  England 
is  that  manufactured  by  Mr.  L.  Casella,  of  174  Holborn,  Bars,  Lon- 
don, E.  C.,  and  it  is  in  all  probability  as  accurate  and  reliable  in  its 
indications  as  any  on  the  market. 

The  instrument  consists,  as  Fig.  10  shows,  of  a  dial  with  revolving 
indicators,  connected  by  clock-works  with  the  propeller-like  fan  that 
revolves  when  exposed  to  a  current  of  air.  According  to  the  rate  at 
which  the  fan  revolves,  a  velocity  varying  from  i  foot  to  10,000,000 
feet  in  a  given  time  can  readily  be  determined  from  the  indications 
on  the  dial  in  a  few  minutes. 

Each  division  passed  by  the  long  hand  on  the  large  circle  repre- 
sents i  foot  traversed  by  the  current  of  air.  In  setting  down  a 
reading  of  the  hands,  the  long  hand  takes  the  units  and  tens  places. 
The  five  other  hands  follow,  respectively. 

Example : 


Milns. 

ioo  Thds. 

10  Thds. 

Thds. 

Hds. 

Long  hand. 

Reading  of  the  diagram 

i 

I 

9 

o 

9Q 

Any  one  not  familiar  with  metric  dials  must  observe  that  the 
figures  read  rationally;  thus,  if  the  feet  hand  is  at  99,  the  hundreds 
hand  will  be  near  the  figure  it  is  approaching.  This  figure  must  not 
be  taken,  but  the  previous  one  that  is  passed. 

A  catch  is  placed  on  the  rim  of  the  instrument  to  enable  the  ob- 
server to  throw  the  indicating  wheels  in  or  out  of  gear  from  the  fan,  for 

the  purpose  of  taking  short  observations  with  accuracy. 

• 

TO    USE    THE    INSTRUMENT. 

Press  the  catch  home  to  the  right  hand,  and  the  fan  will  revolve 
without  moving  the  indicators  on  the  dial.  Now  take  a  careful  read- 
ing from  the  face  of  the  instrument  and  write  it  down;  place  the  instru- 
ment in  the  air  current  and  allow  the  fan  to  revolve  freely  for  a  short 
time,  care  being  taken  that  the  current  strikes  the  fan  at  right 
angles  with  its  plane.  With  a  watch  open  let  the  instrument  run  freely 
until  the  second  hand  of  the  watch  indicates  a  full  minute  when  the 
anemometer  is  to  be  thrown  into  gear  by  pressing  the  catch  to  the 
left.  At  this  instant  the  hands  on  the  dial  begin  to  record  and  continue 
until  the  instrument  is  again  thrown  out  of  gear,  which  in  practice  is 
usually  after  exactly  one  minute.  Another  reading  from  the  dial  is 


164 


ANEMOMETERS. 


now  carefully  made  and  the  difference  between  this  leading  and  that 
made  before  the  instrument  was  thrown  into  gear  gives  the  number  of 
feet  of  air  that  has  passed  over  the  instrument  during  the  time  for 
which  it  was  recording.  For  example  : 

Reading  before  the  instrument  was  in  gear 10,685  feet. 

Reading  after  instrument  has  been  recording  for  one  minute 12,432  feet. 

Number  of  feet  of  air  passing  over  the  instrument  in  one  minute. .   1,747  feet. 

These  figures,  however,  are  simply  those  taken  from  the  dial,  and 
as  every  instrument,  no  matter  how  delicately  constructed,  presents 
more  or  less  friction,  there  must  be  a  correction  for  this.  This  correc- 
tion varies  with  different  instruments,  so  that  for  each  instrument  a 
certain  number  of  feet  must  be  added.  For  example,  if  in  the  anemom- 
eter from  which  the  above  readings  were  taken  there  was  an  addi- 
tional correction  of  25  feet  for  each  minute  that  it  had  been  running, 
the  velocity  of  the  current  of  air  tested  would  be  1,747  -f-  25  =  1,772 
feet  per  minute. 

In  using  the  instrument  care  must  be  taken  that  the  fan  is  not 
bent  or  injured,  and  that  the  bearings  are  all  properly  cleaned  and 
oiled. 

Where  the  instrument  is  employed  for  determinations  of  quantities 
greater  than  those  concerned  in  the  study  of  ventilation,  Mr.  Casella 
has  prepared  the  following  table: 

TABLE  SHOWING  THE  NUMBER  OF  MILES  PER  HOUR  AT  VELOCITIES  PER  MINUTE. 


Feet  per  Minute. 

Miles  per  Hour. 

Feet  per  Minute. 

Miles  per  Hour. 

10 

.113 

600 

6.818 

20 

.227 

700 

7-954 

30 

•  340 

800                                   9.090 

40 

•  454 

900 

10.227 

50 

.568 

I.OOO 

11.363 

60 

.681 

2,000 

22.727 

70 

•  795 

3,000 

34.090 

80 

.909 

4,000 

45-454 

90 

1.022 

5,000 

56.818 

100 

I  .136 

6,000 

68.181 

200 

2.272 

7,000 

79-545 

300 

3.409 

8,000 

90.909 

400 

4-545 

9,000 

102.272 

500 

5.681 

IO.OOO 

113.636 

The  form  of  dynamic  anemometer  most  frequently  employed  in 
Germany  is  that  of  Combes  and  Recknagel.    In  general  principle  it  is  the 


ANEMOMETERS. 


165 


same  as  that  of  Casella,  but  is  by  no  means  an  instrument  of  such 
elegant  appearance. 

In  general  the  same  can  be  said  for  this  apparatus  as  has  been  said 
for  the  Casella  instrument.  Its  construction  can  best  be  understood  by 
the  figures  shown  below. 

In  general  it  consists  of  a  very  light  propeller-like  fan  or  wheel 
the  revolutions  of  which  are  recorded  in  terms  of  meters  and  fractions 
of  meters  upon  a  dial  with  which  it.  is  connected  by  a  system  of  cogs. 

Still  another  application  of  the  same  principle  is  employed  in  the 
anemometer  of  Robinson,  in  which,  instead  of  a  revolving  propeller- 
like  wheel  or  fan,  there  are  cupped  radii  of  a  circle. 

With  each  anemometer  as  it  comes  from  the  manufacturer  there  is 
usually  a  correction  which  is  to  be  added  to  the  readings  obtained 
from  the  dial  in  order  to  obtain  the  exact  result.  This  correction  is 
necessitated  by  the  friction  experienced  by  the  gearing  of  the  ap- 
paratus while  running. 


COMBES'  ANEMOMETER. 


RECKNAGEL'S  ANEMOMETER. 


With  use  the  bearings  of  the  apparatus  gradually  become  worn, 
so  that  it  becomes  necessary  to  control  the  correction  from  time  to 
time  by  testing  the  anemometer. 

A  variety  of  methods  are  employed  for  this  purpose,  but  a  simple 
test,  though  not  without  possible  errors  can  always  easily  be  made 
as  no  instrument  but  a  tape  line  and  a  large  closed  Troom  —  the 
larger  the  better  —  is  necessary.  A  track  around  the  room  of  ico 
feet  or  any  other  convenient  distance  is  measured.  Then  holding 
the  anemometer  at  arm's  length  on  a  small  rod  at  right  angles  to 
the  way  you  face,  go  around  the  track  in  different  directions  and  at 
different  speeds,  noting  the  error,  whether  fast  or  slow.  By  reversing 
the  direction  of  motion  about  the  track,  the  effect  of  local  currents  in 
the  room  is  eliminated  and  the  danger  of  setting  all  the  air  in  motion 
in  one  direction  around  the  room  is  avoided.  If  an  anemometer  is 


l66  ANEMOMETERS. 

held  before  the  operator,  or  near  enough  to  his  body  so  that  his 
motion  will  affect  the  air  which  the  anemometer  is  passing  through 
the  experiment  will  not  be  reliable.  There  are  other  methods,  but 
they  require  special  contrivances.* 

Of  practical  importance  to, those  wishing  to  obtain  an  anemometer 
is  the  advice  given  by  Mr.  Gieseler  in  the  communication  referred  to  in 
the  foot  note.  He  states:  "Those  with  agate  bearings  will  not  only 
wear  longer  and  run  with  less  resistance,  but  the  possession  of  such 
a  bearing  is  of  itself  an  evidence  of  better  workmanship  and  material 
than  is  to  be  expected  in  those  which  are  not  so  fitted,  which,  as  a  rule, 
are  not  worth  purchasing  at  any  price." 

In  the  study  of  ventilation  the  only  use  that  is  made  of  the  static 
forms  of  anemometers  is  as  constant  indicators  of  the  pressure  of  air 
currents,  which  pressure  as  indicated  upon  the  face  or  dial  of  the  in- 
strument, corresponds  with  a  certain  velocity  that  has  been  previously 
determined  by  comparison  with  a  correct  dynamic  anemometer. 

If  one  has  a  dynamic  anemometer  with  which  to  control  and 
correct  their  static  apparatus,  it  is  a  very  easy  matter  to  construct  an 
instrument  that  can  be  fixed  permanently  in  the  course  of  the  air 
current  and  give  at  all  times  fairly  accurate  indications  of  the  velocity 
of  the  current  that  is  causing  the  fan  of  the  apparatus  to  deflect. 

An  anemometer  that  requires  no  special  skill  in  its  employment, 
and  at  the  same  time  gives  results  which  approximate  so  closely  to 
those  obtained  through  the  use  of  more  elaborate  instruments  as  to 
make  it  of  considerable  value  in  rapidly  judging  the  approximate 
amount  of  air  passing  into  a  room  through  the  registers,  may  be  easily 
constructed,  as  shown  by  the  following  figures. 

The  instrument  is  made  of  cork,  paper  and  broom  straws.  It  con- 
sists of  an  ordinary  cork  (A)  from  which  is  made  to  swing  at 
the  point  E,  a  paper  fan  c  suspended  upon  the  arm  B,  which  is  simply 
a  thin  light  broom  straw.  At  ^the  arm  B  swings  upon  a  fine  cambric 
needle,  so  that  there  is  very  little  friction,  and  the  fan  is  caused  to 
swing  under  the  pressure  of  the  lightest  draught.  D  is  a  quadrant 
divided  into  equal  parts.  It  is  made  fast  to  the  cork  A,  and  registers 
the  distance  which  the  fan  c  swings  out  of  the  line  of  perpendicular. 
By  comparison  with  an  exact  instrument  the  values  of  the  markings  on 
the  quadrant  may  be  established,  and  these  values  recorded  upon  the 
different  radii.  These  values  being  established,  one  has  then  but  to  insert 

*  See  Sanitary  Engineer,  March  10,  1888. 

For  a  more  extensive  discussion  upon  The  Testing  of  Anemometers  see 
Sanitary  Engineer,  July  13,  1889.     Communication  from  Mr.  E.  A.  Gieseler. 


ANEMOMETERS. 


T''!I' ill  HI  Hi M 

IF  |ic 

P  '    i  r 


FIG. 


FIG.  12. 


FIG.  13. 


i68 


ANEMOMETERS. 


the  cork  A  into  an  opening  on  the  face  of  the  register,  and  observe  the 
distance  which  the  incoming  air  causes  the  fan  c  to  swing  from  the  per- 
pendicular. This  distance  corresponds,  as  maybe  seen  upon  the  quad- 
rant, to  the  pressure  of  the  air  at  different  velocities.  The  clear  opening 
of  the  register  being  known,  it  is  then  easy  to  calculate  the  amount  of 
air  expressed  in  cubic  feet  per  second  passing  through  the  register. 

Fig.  ii  represents  the  instrument  in  profile. 
Fig.  12  "         seen  from  the  front  view. 

Fig.  13  "  »*  "         showing  deflection  of  the  fan  (indicator) 

under  pressure  of  incoming  air. 

A  somewhat  more  elaborate  form  of  the  same  apparatus  has 
recently  been  devised  by  Fuess,  of  Berlin.  It  is  intended  to  be  placed 
permanently  upon  the  wall  surface  of  a  flue,  with  its  fan  projecting  in- 


FIG.  14. 


FIG. 


side  and  exposed  to  the  action  of  the  currents  passing  up  the  flue. 
The  deflections  of  the  fan  are  indicated  by  a  pointer  that  traverses  an 
arc  upon  the  face  of  the  apparatus. 

By  the  use  of  this  apparatus  one  can  see  at  a  glance  upon  entering 
a  room,  in  which  the  apparatus  is  placed,  the  velocity  of  the  air 
passing  up  the  flue,  as  indicated  by  the  position  of  the  pointer  on  the 
arc.  The  apparatus  is  seen  in  Figs.  14  and  15. 

These  show  a  transverse  section  of  the  knife  edge  that  passes 
through  the  hollow  tube  s,  and  carries  on  the  face  of  the  apparatus 
the  pointer  a,  and  on  the  other  end  that  projects  into  the  flue 
the  fan  /.  b  and  b'  are  sliding  weights  by  which  equilibrium  and 
adjustment  are  maintained.  c  is  a  vessel  containing  glycerine,  in 
which  floats  a  counterpoise  for  the  weight  b.  R  is  the  arc  traversed 


AIR    CURRENTS.  169 

by  the  pointer  a,  and  marked  at  intervals  with  lines  indicating  the 
velocity  of  a  current  that  causes  the  different  degrees  of  deflection. 

In  the  use  of  anemometers  there  are  several  points  to  be  borne  in 
mind. 

The  apparatus  must  always  be  clean  and  well  oiled.  The  plane  of 
its  revolving  fan  must  be  at  right  angles  to  the  direction  of  the  air  cur- 
rent, and  must  be  free  in  the  current  so  as  not  to  be  influenced  by 
eddies  caused  by  the  friction  of  the  air  against  surrounding  objects. 

When  used  for  the  determination  of  currents  of  air  passing  up 
flues  or  through  registers,  one  observation  is  not  sufficient  for 
accuracy,  but  a  mean  of  several  observations  made  at  the  corners  and 
center  of  the  flue  or  register  must  be  taken. 

The  results  should  be  those  obtained  after  an  exposure  of  the  in- 
strument to  the  current  of  not  less  than  one  minute  for  each  observa- 
tion. 

To  determine. the  direction  of  the  air  currents  within  the  room, 
smoke  is  commonly  used.  This  smoke  may  be  produced  by  burning 
tobacco,  or  cotton  velvets,  or  lamp  wick  saturated  with  benzoin,  etc.,  or 
by  igniting  a  little  slightly  moistened  gunpowder.  The  fumes  of  nascent 
muriate  of  ammonia  are  in  some  respects  preferable  to  smoke,  since 
they  are  of  the  same  temperature  as  the  air  and  can  injure  nothing  in 
the  room.  They  are  produced  by  pouring  a  little  liquor  ammoniae  into 
a  capsule  or  saucer  and  surrounding  this  with  a  sheet  of  common 
blotting  paper  about  6  inches  wide,  pinned  into  the  shape  of  a  shirt 
cuff  and  saturated  with  diluted  hydrochloric  acid.  Filaments  of  floss 
silk  suspended  from  a  rod,  furnish  a  delicate  test  for  air  currents.  Toy 
balloons  are  rarely  of  much  use  for  this  purpose  and  the  flame  of  a 
candle  is  not  sufficiently  easy  to  move. 

For  producing  smoke  to  test  direction  and  velocity  of  air  currents 
Pettenkofer  uses  cotton  lamp  wick,  which  has  been  boiled  for  several 
hours  in  a  6  per  cent,  solution  of  nitrate  of  potash,  then  thoroughly 
dried  at  100°  C.,  then  steeped  for  several  hours  in  an  alcoholic  solution 
of  gum  benzoin,  and  then  dried  at  ordinary  temperatures. 

While  observations  as  to  the  direction  and  velocity  of  air  currents 
in  a  room  can  give  only  approximate  information  as  to  the  condition 
of  the  ventilation,  and  should  always  be  supplemented  by  the  chemical 
method,  they  are,  nevertheless,  much  more  satisfactory  than  opinions  as 
to  whether  the  ventilation  of  a  given  building  is  good  or  bad,  founded 
not  on  any  tests  as  to  quality  or  quantity  of  air,  but  on  personal  sensa- 
tions, which  in  most  cases  are  due  rathex  to  temperature  than  anything 
else.  People  are  apt  to  suppose  that  a  cool  room  must  be  a  well-ven- 


170  MEASUREMENT    OF    VENTILATION. 

tilated  room  and  that  when  they  are  too  hot  the  air  must  be  impure. 
It  is  true  that  an  overheated  room  is  not  a  properly-ventilated  room  if 
the  temperature  of  the  external  air  is  below  70°  F.,  for  one  of  the 
objects  of  ventilation  is  to  produce  a  comfortable  temperature;  but 
hot  air  may  be  pure,  and  cool  air  dangerously  impure.  As  was  men- 
tioned in  the  section  on  quantity  of  air  required,  the  normal  sense  of 
smell  is  an  excellent  means  of  judging  of  the  sufficiency  of  ventilation 
of  a  closed  room  occupied  by  human  beings,  but  to  have  this  sense 
normal  the  person  must  come  in  from  the  fresh  outside  air,  and  not 
have  remained  in  the  room  more  than  a  very  few  minutes. 

The  amount  of  ventilation  going  on  in  an  apartment  at  any 
moment  may  be  determined  either  by  direct  measurement  of  the 
velocity  with  which  the  air  enters  and  leaves  through  openings  espe- 
cially designed  for  its  entrance  and  exit,  or  by  a  systematic  series  of 
chemical  analyses  of  the  air  made  at  stated  intervals  for  a  certain 
period  of  time. 

If  the  method  of  direct  measurement  of  the  velocity  of  the  in- 
coming and  outgoing  currents  is  selected,  the  procedure  is  a  simple 
one,  though  the  results  thus  obtained  can  only  be  considered  as  ap- 
proximate, because  of  the  leakage  through  cracks  about  doors,  windows, 
etc.,  where  it  is  impossible  to  measure  accurately  the  amount  of  ex- 
change going  on. 

In  the  determination  through  the  aid  of  anemometers  the  exact 
areas  of  the  inlet  and  outlet  for  air  entering  and  leaving  the  room  are 
to  be  ascertained  by  measurement,  and  by  means  of  the  anemometer 
the  velocity  of  the  currents  passing  through  them  is  determined  for 
a  given  length  of  time,  one  minute  being  the  time  usually  selected. 
By  dividing  the  result  of  the  observation  by  60  or  multiplying  it  by  60 
we  obtain  the  amount  of  air  entering  and  leaving  the  room,  through 
the  ventilators,  per  second  or  per  hour.  From  the  cubic  capacity  of 
the  room  it  is  then  easy  to  determine  the  number  of  times  per  hour  the 
whole  volume  ot  air  is  being  renewed. 

In  this  method  all  windows  and  doors  opening  into  the  room 
must  be  closed,  and  only  those  openings  intended  for  the  passage  of 
air  be  allowed  to  remain  open. 

In  measuring  the  velocity  of  these  currents  it  is  customary  to  make 
five  observations  at  each  opening.  The  anemometer  is  to  be  held  at 
the  center,  and  at  four  diametrically  opposite  points  near  the  periphery 
of  the  opening.  Each  determination  is  to  be  for  one  minute,  and  an 
average  of  the  five  observations  taken  as  the  velocity  of  the  whole 
current  per  minute. 


MEASUREMENT    OF    VENTILATION.  171 

Example. — The  room  measures  lo'xia'xio'  =  1,200  cubic  feet 
capacity.  Observations  at  either  inlet  or  outlet  ventilators  as  follows: 

Center  =  64  feet  per  minute. 

Top  edge        =  58     "      " 
Bottom  edge  =  59     " 
Right  side       =  59     " 
Left  side         =  60     " 

300  -r-  5  —  60  feet  per  minute  average. 

By  measurement  our  ventilators  are  found  to  have  a  clear  trans- 
verse area  of  i  square  foot.  We  have,  therefore,  i  square  foot 
area  X  60  feet  per  minute  velocity  =  60  cubic  feet  per  minute 
passing  through  the  opening;  for  one  hour  we  should,  therefore,  have 
3,600  cubic  feet  passing  through.  The  capacity  of  our  room  is  ,1,200 
cubic  feet.  Therefore,  this  volume  of  air  is  being  completely  renewed 
at  the  rate  of  three  times  per  hour  as  shown  at  the  air  inlets  or  outlets 
where  it  is  possible  to  measure  directly  the  velocity  of  the  incoming 
currents. 

The  chemical  method  suggested  by  von  Pettenkofer  for  the 
study  of  ventilation  has  the  advantage  over  the  method  just  described, 
in  determining  the  entire  exchange  of  air  going  on;  including  not  only 
the  amount  passing  in  and  out  through  the  ventilators,  but  likewise  that 
escaping  through  cracks  about  the  doors  and  windows.  It  gives,  there- 
fore, much  more  exact  results  than  can  be  obtained  through  direct 
measurement. 

It  is  based  upon  the  fact  that  if  in  a  closed  room  we  have  any 
easily  recognizable  gas,  the  amount  of  fresh  air  entering  the  room  in  a 
given  time  may  be  determined  by  the  dilution  experienced  by  the  gas 
in  this  time. 

As  a  characteristic  gas  Pettenkofer  recommends  carbonic  acid. 
He  closes  all  openings  into  the  room  and  then  artificially  generates  an 
excessive  amount  of  this  gas  in  the  air  of  the  room.  After  thoroughly 
mixing  by  means  of  fans,  the  amount  of  carbonic  acid  present  is  de- 
termined. The  ventilators  are  then  to  be  opened  and  at  equal  inter- 
vals for  a  given  time  analyses  are  again  made  and  from  the  diminution 
in  the  amount  of  the  gas  present  the  rate  of  inflow  of  fresh  air  is  de- 
termined. As  source  for  the  production  of  the  carbonic  acid  stearine 
candles  of  good  quality  are  recommended.  Such  candles  when  burn- 
ing give  off  about  2.764  grams  or  1.404  litres  of  CO3  per  gram  of 
candle,  and  burn  at  about  9.6  grams  per  hour. 

In  the  apartment  to  be  studied  a  number  of  such  stearine  candles 
are  to  be  burned.  Their  number  and  the  time  necessary  for  the  pro- 


172  MEASUREMENT    OF    VENTILATION. 

duction  of  an  excess  of  CO2  is  to  be  calculated  from  the  preceding  fig- 
ures for  this  rate  of  production.  Or,  as  has  been  recommended  by 
Petri  (Zeitschrift  f.  Hygiene,  Bd.  VI.),  fluid  carbonic  acid  may  be  lib- 
erated in  the  room.  When  the  experiment  is  begun,  the  air  of  the 
room  should  contain  this  gas  in  the  proportion  of  about  5  to  6  parts 
per  1,000,  the  exact  amount  being  determined. 

The  doors  and  windows  are  kept  closed,  and  samples  of  air  are  to 
be  taken  from  about  the  center  of  the  room  at  intervals  of  30  minutes 
for  one  hour  after  the  ventilators  are  opened. 

In  taking  these  samples,  it  is  well  to  obtain  them  through  a  tube 
passing  through  a  small  opening  into  the  center  of  the  room.  The 
tube  may  pass  into  the  room  either  through  the  keyhole  of  the  door  or 
through  an  opening  made  at  the  floor  level.  The  samples  of  air  may 
then  be  drawn  by  means  of  an  aspirator  into  flasks  intended  for  the 
purpose,  without  the  door  to  the  room  being  opened. 

When  the  necessary  number  of  samples  have  been  collected  and 
analyzed,  the  calculation  for  the  rate  at  which  ventilation  has  been 
going  on  is  made  from  the  formula  of  Seidel  : 

x  =  2.303  X  m  X  log.  £L—  —, 

in  which 

m  =  cubic  contents  of  the  room. 

/j  =  amount  of  CO2  present  at  the  beginning  of  experiment. 

a  =  "  in  open  air. 

x  =  amount  of  air  which  has  passed  into  the  room. 
Example.— -By  the  method  of  analysis  for  the  determination  of 
carbonic  acid,  it  was  found  that  the  air  of  a  room  contained  : 

At  the  beginning  —  3.590  %  CO2. 
After  30  minutes  —  3.170  %  CO2. 
After  60  minutes  —  2.806  %  CO2. 
Open  air  — o.35o$CO2. 

Cubic  contents  of  room,  1,200  feet. 
x  =  amount  of  ventilation  going  on. 
For  the  first  half  hour  : 


.  . 

x  ~  2.303  x   1,200  X   log.      ^   Q  _  00  —  2-3°3  x  I»200  x  0.06032 

=  166.7  cubic  feet  of  air  passed  in  during  first  half  hour. 
And  for  the  second  half  hour  : 


x  =  2.303  X   1,200  X  log.     '  ~  =  2.303  X   1,200  X  0.05994 

=  165.7  cubic  feet  of  air. 


AMOUNT    OF    AIR    REQUIRED.  173 

Therefore,  for  the  entire  hour,  we  have  166.7  +  J^5-7  —  232-4 
cubic  feet  of  air  passing  into  a  room  of  1,200  cubic  feet  capacity.  At 
this  rate  the  entire  volume  of  air  in  the  room  would  require  5.2  hours 
for  its  complete  removal,  a  rate  of  ventilation  quite  inadequate  for 
purposes  of  comfort. 

This  method  meets  its  greatest  application  in  apartments  which 
depend  for  their  air  supply  entirely  upon  that  afforded  through  the 
channel  of  "  natural  ventilation."  Though  more  exact  than  the  actual 
measurement  of  the  amount  of  incoming  air,  still  the  detail  involved  in 
its  performance  renders  it  of  less  universal  application. 

It  should  also  be  borne  in  mind  that  when  this  method  is  used  for 
determining  the  amount  of  ventilation  of  rooms  provided  with  air  in- 
lets, provision  must  be  made  for  opening  and  closing  these  inlets  by 
cords  from  without,  for  the  accuracy  of  the  results  will,  of  course,  be 
destroyed  if  doors  be  opened. 

For  the  determination  of  the  number  of  cubic  feet  of  air  required 
'per  head  per  hour  in  inhabited  apartments,  De  Chaumont  proposes 
the  following  formula: 


in  which 

e  —  amount  of  CO2  exhaled  hourly  by  adults  expressed  in  cubic 
feet. 

/  —  the  limit  of  admissible  impurity. 

d  =  amount  of  fresh  air  required  per  hour. 

Taking  0.6  cubic  feet  as  the  average  amount  of  CO2  exhaled  by  an 
adult  in  one  hour,  and  0.0002  as  the  exponent  of  admissible  impurity 

from  human  exhalation,  we  have  - —   —   —  d  =  3,000  cubic  feet,  the 

0.0002 

amount  of  fresh  air  which  should  be  delivered  to  each  adult  in  one 
hour. 

The  actual  amount  of  fresh  air  being  supplied  may  be  calculated 
by  substituting  for  the  admissible  impurity  the  actual  impurity.  Thus, 
suppose  we  find  the  air  to  contain  0.7  parts  CO2  in  1,000,  we  then 

have  —  -  =  857  as  the  number  of  cubic  feet  of  air  being  supplied  per 

hour. 

Or  if  the  proportion  of  carbonic  acid  present  in  the  air  of  a  room 
be  required  and  the  rate  of  delivery  of  the  air  be  known,  it  may  be 
calculated  from  the  same  formula,  thus,  substituting  in  the  above 


174  AMOUNT    OF    AIR    REQUIRED. 

formula  pl  as  representing  the  actual  amount  of  this  gas  present  for/, 
which  represents  the  admissible  limit  of  impurity,  we  have 

—  =  d,  hence 


Taking  again  0.6  as  the  number  of  cubic  feet  of  CO2  exhaled  per 
hour  by  adult  individuals,  and  1,200  cubic  feet  per  hour  as  the  rate  at 
which  air  is  entering  the  apartment,  we  have 

—  -  -  •  =  0.0005  CO9  per  cubic  foot. 

1,200 

or  5  parts  in  10,000. 

In  all  these  formulae  the  value  of  e  must  be  changed  with  different 
conditions:  For  children  it  averages  0.4;  for  adults  under  ordinary 
conditions  it  is,  as  stated,  0.6;  for  adult  males  alone,  as  for  example,' 
soldiers  in  barracks,  0.72  is  suggested  as  the  average  hourly  exhalation 
of  carbonic  acid  in  cubic  feet. 

In  discussing  the  relation  of  atmospheric  moisture  to  ventilation, 
De  Chaumont  (Proc.  Royal  Soc.,  London,  Vol.  XXV.,  1876-77,  p.  n), 
states  that  an  increase  of  i  per  cent,  of  humidity  has  as  much  influ- 
ence on  the  condition  of  an  air  space  (as  judged  of  by  the  sense  of 
smell)  as  a  rise  of  4.18  degrees  of  temperature  in  Fahrenheit's  scale. 
This  may  be  taken  as  a  proof  of  the  powerful  influence  exercised  by  a 
damp  atmosphere,  corroborating  the  conclusions  arrived  at  by  ordinary 
experience;  and  it  follows  that  as  much  care  ought  to  be  taken  to  in- 
sure proper  hygrometric  conditions  as  to  maintain  a  sufficiently  high 
temperature.  This  is  especially  the  case  in  the  wards  or  chambers  of 
the  sick,  in  which  regular  observations  with  the  wet  and  dry-bulb 
thermometers  ought  to  be  made;  these  would  probably  give  a  valuable 
indication  of  the  ventilation  either  along  with  or  in  the  absence  of 
other  more  detailed  investigations.  Thus,  a  room  at  the  temperature 
of  60°  F.  and  with  88  percent,  of  humidity,  contains  5.1  grains  of 
vapor  per  cubic  foot;  suppose  the  external  air  to  be  at  50°  F.  with 
the  same  humidity  —  88  per  cent.  —  this  would  give  3.6  grains  of  vapor 
per  cubic  foot;  to  reduce  the  humidity  in  the  room  to  73  per  cent.,  or 
4.2  grains  per  cubic  foot,  we  must  add  the  following  amount  of 
external  air: 


CARBONIC    ACID    TEST.  1 75 

or  once  and  a  half  the  volume  of  air  in  the  room.  If  the  inmates  have 
each  1,000  cubic  feet  of  space,  it  follows  that  either  their  supply  ^of 
fresh  air  is  short  by  1,500  cubic  feet  per  head  or  else  that  there  are 
sources  of  excessive  humidity  within  the  air  space  which  demand 
immediate  removal. 

In  what  would  be  termed  "  pure  country  air,"  carbonic  acid  is 
present  in  the  proportion  of  about  3  parts  in  10,000.  In  a  crowded 
and  confined  space,  such  as  the  pit  of  a  theater  and  in  some  school- 
rooms, its  proportion  has  been  found  to  rise  to  30,  40,  and  even  100 
parts  per  10,000. 

Pure  carbonic  acid  gas  maybe  present  in  air  in  a  proportion  as  high 
as  150  parts  per  10,000,  without  producing  discomfort  or  giving  any 
special  evidence  of  its  presence,  as,  for  instance,  in  those  establish- 
ments where  sparkling  mineral  waters  are  bottled,  or  soda  fountains 
are  charged,  or  in  vaults  where  champagne  is  bottled,  in  certain  rooms 
in  breweries,  or  in  some  celebrated  baths  and  health  resorts. 

It  is  evident,  therefore,  that  carbonic  acid  gas — in  the  proportions 
in  which  we  find  it  in  our  worst  ventilated  rooms — is  not  in  itself  a 
dangerous  impurity  ;  in  fact,  we  have  no  evidence  to  show  that  in  such 
proportions  it  is  even  injurious. 

What,  then,  is  the  importance  of  this  gas  in  relation  to  questions 
of  ventilation  ?  and  why  do  sanitarians  lay  so  much  stress  upon  the 
results  of  chemical  tests  of  air  with  reference  to  this  substance,  and  on 
what  may  seem  very  small  variations  in  the  proportions  in  which  it  is 
present  ? 

It  is  because  carbonic  acid  is  usually  found  in  very  bad  company, 
and  that  variations  in  its  amount  to  the  extent  of  3  or  4  parts  in 
10,000  indicate  corresponding  variations  in  the  amount  of  those  gases, 
vapors  and  suspended  particles,  which  are  really  offensive  and  danger- 
ous ;  and  also  because  we  have  tests  by  which  we  can,  with  compara- 
tive ease  and  certainty,  determine  the  variations  in  the  carbonic  acid, 
while  we  have  no  such  tests  of  recognized  practical  utility  for  the 
really  dangerous  impurities. 

As  a  matter  of  convenience,  therefore,  we  measure  the  carbonic 
acid,  and  thus  get  a  measure  of  the  extent  to  which  ventilation  is  being 
effected.  Of  course,  we  must  make  sure  that  the  circumstances  of  the 
case  present  nothing  unusual,  since,  on  the  one  hand,  carbonic  acid 
may  be  present  in  great  excess,  as  in  a  soda-fountain-charging  room, 
without  indicating  great  impurity  ;  and,  on  the  other,  it  is  possible  that 
the  air  of  a  room  may  be  very  dangerous  from  suspended  organic 
particles,  and  yet  have  carbonic  acid  present  in  merely  normal 


176  CARBONIC    ACID    TEST. 

amount.  This  will  appear  more  clearly  when  we  come  to  consider  the 
ventilation  of  hospitals  for  infectious  diseases. 

But  while  the  quantity  of  carbonic  acid  which  is  contained  in  some 
of  our  worst  ventilated  rooms  is  not  injurious  to  human  life,  the  amount 
of  this  gas  present  is  nevertheless  of  very  great  importance  in  relation 
to  ventilation,  and  very  small  variations  in  it — even  so  little  as  one 
ten-thousandth  part— are  often  very  significant,  because  we  measure 
by  it  the  quantity  of  organic  impurities  present,  since  we  cannot  con- 
veniently measure  these  impurities  themselves. 

In  most  treatises  on  ventilation  we  are  told  that  the  best  test  for 
the  presence  of  an  undue  amount  of  impurity  in  the  air  is  the  sense 
of  smell.  When  a  person  goes  from  the  fresh  outer  air  into  an  inhab- 
ited room,  and  does  not  perceive  any  special  odor,  it  is  usually  safe 
to  assert  that  that  room  is  well  ventilated.  But  while  this  is  true,  it  is 
necessary  to  have  some  other  test  which  will  be  independent  of  indi- 
vidual peculiarities,  and  the  results  of  which  can  be  demonstrated  to 
others.  The  man  who  has  a  patent  sanitary  stove,  or  an  automatic 
ventilator,  will  rarely  find  any  disagreeable  odor  in  a  room  fitted  with 
his  appliances.  The  carbonic  acid  test  for  foul  air  depends  upon  the 
fact  that  when,  as  the  product  of  respiration,  the  proportion  of  car- 
bonic acid  in  a  room  increases  from  the  normal  amount  of  about  3 
parts  in  10,000  to  between  6  and  7  parts  in  10,000,  a  faint,  musty, 
unpleasant  odor  is  usually  perceptible  to  one  entering  from  the  fresh 
air.  If  the  proportion  reaches  8  parts  the  room  is  said  to  be  close. 

To  secure  entirely  satisfactory  ventilation  which  will  prevent  this 
odor,  the  proportion  of  carbonic  acid  derived  from  respiration,  or  what 
is  sometimes  called  the  "  carbonic  impurity,"  should  never  exceed 
2,  or,  at  the  utmost,  3  parts  in  10,000  of  the  air  in  a  room;  that 
is,  if  the  proportion  in  the  fresh  air  be  4,  that  in  the  foul  air  must 
not  exceed  7.  The  testing  the  amount  of  carbonic  acid  present 
is,  although  a  simple  operation,  one  which  requires  much  care  and 
precision  throughout.  In  collecting  the  sample  of  air  for  examination, 
special  precautions  are  required,  since,  if  any  one  has  his  head  too 
close  to  the  jar,  or  if  several  persons  gather  around  to  see  what  is  go- 
ing on,  the  sample  will  show  too  high  a  proportion  of  carbonic  acid. 

For  ordinary  purposes  a  convenient  method  of  testing  the  amount 
ot  carbonic  acid  is  that  of  Smith,  for  which  there  will  be  needed  six 
well-stoppered  bottles,  containing  respectively  450,  350,  300,  250,  200 
and  100  cubic  centimeters,  a  glass  tube  or  pipette  graduated  to  contain 
exactly  15  cubic  centimeters  to  a  given  mark,  and  a  bottle  of  perfectly 
clear  and  transparent  fresh  lime  water.  The  bottles  must  be  perfectly 


AIR    TESTERS.  177 

clean  and  dry.  Having  made  sure  that  they  are  filled  with  the  atmos- 
phere which  is  to  be  examined,  which  can  best  be  done  by  pumping 
into  them  a  quantity  of  this  air  by  means  of  one  of  the  small  handball 
syringes,  which  may  be  procured  in  any  drug  store,  and  taking  care 
that  none  of  your  own  breath  is  pumped  in,  add  to  the  smallest  bottle 
by  means  of  the  pipette,  15  cubic  centimeters  of  the  lime  water,  put  in 
the  cork,  and  shake  the  bottle.  If  turbidity  appears,  the  amount  of 
the  carbonic  acid  will  be  at  least  ib  parts  in  10,000.  If  no  turbidity 
appears,  treat  the  next  sized  bottle — viz.,  of  200  cubic  centimeters,  in 
like  manner.  Turbidity  in  this  would  indicate  12  parts  in  10,000.  If 
this  remains  clear,  but  turbidity  is  produced  in  the  250  cubic  centi- 
meter bottle,  it  marks  about  10  in  10,000.  The  300 
cubic  centimeter  bottle  indicates  8  parts,  the  350  7  parts, 
and  the  450  less  than  6  parts.  To  judge  of  the  turbidity, 
mark  a  small  piece  of  paper  on  the  inside  with  a  cross  in 
lead  pencil,  and  gum  to  the  side  of  the  bottle  on  the 
lower  part.  When  the  water  becomes  turbid  the  cross 
will  become  invisible  when  looked  at  through  the  water. 
This  will  enable  one  to  judge  roughly  of  the  amount  of 
carbonic  acid  in  the  air.  For  more  accurate  analysis  the 
processes  can  best  be  learned  by  spending  about  three 
hours  a  day,  for  three  or  four  days,  in  a  laboratory, 
working  under  the  directions  of  a  good  chemist. 

Another  instrument,  which  is  claimed  to  be  the 
simplest  and  cheapest  means  of  making  an  approximate 
estimate  as  to  the  proportion  of  carbonic  acid  contained 
in  air,  is  one  devised  by  Professor  Wolpert,  and  called 
by  htm  an  air  tester.  This  consists  of  a  test  tube, 
marked  near  the  bottom  to  show  the  point  to  which  it 
must  be  filled  to  contain  3  cubic  centimeters.  The 
bottom  of  this  tube  is  whitened,  and  on  the  bottom  is 
a  black  mark — or  a  date  printed  in  black.  Clear  lime 
water  is  poured  in  the  tube  to  the  amount  of  3  cubic 
centimeters,  and  the  air  to  be  tested  is  blown  through 
PIG.  16.  tn|s  fluid  until  it  becomes  so  opaque  from  the  formation 

of  carbonate  of  lime  that  the  figure  on  the  bottom  of  the  tube  becomes 
invisible.  The  air  is  blown  through  by  means  of  a  rubber  bulb  con- 
taining 28  cubic  centimeters  fastened  in  a  glass  tube,  the  free  end  of 
which  dips  beneath  the  surface  of  the  lime  water.  See  Fig.  16. 

The  number  of  times  which  this  bulb  must  be  filled  and  emptied 
measures  the  amount  of  air  required  to  produce  the  opacity  above 


/ 


178 


AIR    TESTERS. 


referred  to,  and  a  table  which  accompanies  the  instrument  shows  the 
proportion  of  carbonic  acid  which  corresponds  to  a  given  number  of 
fillings  of  the  bulb.  Thus,  if  the  bulb  has  been  emptied  40  times  to 
produce  opacity,  the  proportion  of  carbonic  acid  present  is  10  parts  in 
10,000;  if  the  bulb  has  been  filled  50  times  the  carbonic  acid  is  4  parts 
per  10,000,  etc.  It  is  claimed  that  with  this  instru- 
ment the  unskilled  observer,  after  three  or  four  trials, 
can  estimate  the  proportion  of  carbonic  acid  present 
to  within  i  part  in  10,000,  which  is  near  enough  for 
practical  purposes.  The  chief  precaution  to  be  taken 
by  the  experimenter  is  to  see  that  in  filling  the  bulb 
with  the  air  of  the  room  he  does  not  draw  into  it  an 
undue  proportion  of  air  which  he  himself  has  just 
exhaled. 

Comparisons  of  results  obtained  by  the  use  of 
this  instrument  with  those  found  by  exact  analyses  of 
the  same  air  show  that  it  is  extremely  unreliable  and 
in  many  cases  the  results  can  hardly  be  considered 
approximate.  The  reason  for  this  is  the  impossibility 
of  causing  the  same  volume  of  air  to  pass  through 
the  fluid  with  each  compression  of  the  rubber  bulb. 
If  exactly  the  same  volume  of  air  were  forced  through 
the  fluid  with  each  compression  there  is  no  reason  why 
fairly  accurate  results  should  not  be  obtained. 

Another  form  of  air  tester,  devised  by  Wolpert 
and  known  as  a  carbacidometer,  is  shown  in  Fig.  17. 
It  consists  of  a  cylinder  graduated  to  50  cubic  centi- 
meters on  the  one  side  and  etched  on  the  other  side 
at  the  level  of  10  cubic  centimeters  with  the  words 
"Uncommonly  bad"  and  the  figure  4;  at  18  cubic 
centimeters  with  "Very  bad  "  and  the  figure  2;  at  33 
cubic  centimeters  with  "Bad  "  and  the  figure  i,  and 
at  47  cubic  centimeters  with  "  Passable  "  and  the 
figure  0.7.  Within  this  cylinder  slides  a  piston  head 
which  fits  snugly  with  a  rubber  packing  and  is  moved 
by  a  glass  piston,  through  which  is  a  capillary  canal. 
In  the  employment  of  the  carbacidometer  a  solution  of  sodium 
carbonate  is  employed  and  phenolphthalein  is  the  indicator  used. 
These  accompany  each  apparatus,  packed  in  small  capsules,  each  of 
which  contains  the  proper  weight  of  material.  Directions  for  making 
the  solution  from  these  compounds  likewise  accompany  each  instru- 


•Ill* 


FIG. 


AIR    TESTERS.  179 

ment.  When  the  solution  is  ready  for  use  it  is  of  a  bright  magenta 
color. 

When  a  test  is  to  be  made  2  cubic  centimeters  of  the  red  solution 
are  placed  in  the  cylinder  and  the  piston  is  replaced  and  pushed  grad- 
ually down  upon  it  until  the  fluid  begins  to  rise  in  the  capillary  canal. 
The  piston  is  then  gradually  withdrawn  until  the  center  of  the  piston 
head  is  opposite  the  words  "  Uncommonly  bad  "  and  the  figure  4.  The 
apparatus  is  then  shaken  by  a  lateral  swinging  motion,  the  finger  being 
held  all  the  while  over  the  outer  extremity  of  the  capillary  opening  in 
the  piston  for  one  minute.  If  at  the  end  of  this  time  no  color  change 
is  seen  the  finger  is  removed  from  over  the  capillary  canal,  the  piston 
is  withdrawn  a  little  further,  to  the  mark  "  Very  bad,"  and  again  shaken 
for  one  minute;  if  at  the  end  of  this  time  the  color  begins  to  fade,  or 
fades  away  entirely,  then  the  air  under  analysis  contains  approximately 
the  amount  of  carbonic  acid  represented  by  the  figure  which  accompa- 
nies the  words  opposite  the  head  of  the  piston,  in  this  case  "  Very  bad  "  is 
equivalent  to  an  air  containing  2  parts  of  carbonic  acid  in  1,000  parts 
of  air.  If  no  disappearance  of  the  color  of  the  solution  is  seen  when 
the  piston  is  withdrawn  until  the  head  is  opposite  the  mark  indicating 
50  c.c.  on  the  cylinder,  the  air  contains  less  than  0.7  parts  CO2  in 
1,000  parts  air,  and  is  considered  good  air. 

The  minute  details  for  the  manipulation  of  the  apparatus  accom- 
pany each  instrument. 

A  third  form  of  apparatus  devised  by  Wolpert,  and  known  as  a 
"continuous  air  tester,"  is,  as  the  name  implies,  intended  to  register  at 
all  times  the  condition  of  the  air  in  the  room  in  which  it  is  placed,  just 
as  a  thermometer  registers  the  respiration.  This  apparatus  consists  of 
a  wooden  stand,  on  the  upper  end  of  which  rests  a  reservoir  containing 
sodium  bicarbonate  solution,  with  phenolphthalein  as  indicator.  Upon 
the  solution  is  a  float  to  which  is  attached  a  syphon  of  such  caliber  that 
it  permits  a  drop  of  the  solution  to  fall  upon  a  cord  which  hangs  in 
front  of  a  porcelain  scale  once  every  100  seconds.  As  the  drop  strikes 
the  cord  and  slowly  trickles  down  it,  the  cord  takes  on  a  red  color, 
which  color  remains  according  to  the  amount  of  carbonic  acid  present 
in  the  atmosphere.  This  gas  converts  the  carbonate  into  the  bicar- 
bonate of  soda,  with  the  ultimate  disappearance  of  "the  color  of  the 
indicator.  The  point  on  the  string  at  which  the  color  disappears  falls 
opposite  a  portion  of  the  porcelain  scale,  on  which  are  the  words, 
"Pure,"  "Passable,"  "  Bad,"  "Very  bad,"  and  "Uncommonly  bad," 
which  correspond  in  the  order  named  to  carbonic  acid  in  1,000  parts 
of  air  in  the  following  proportions  :  0.5  to  0.7,  0.7  to  i.o,  i.o  to  2.0, 


i8o 


MINIMETRIC    METHOD. 


2.0  to  4.0,  and  4.0  or  more.    In  the  work  of  Bitter  (Zeitschr.  f.  Hygiene, 
Bd.  IX.,  1890),  this  apparatus  was  compared  with  exact  methods  of 
analysis,  and  the  results  were  so  irregular  that  Bitter  considers  the 
apparatus  little  better  than  a  toji,  and  of  little  or  no  hygienic  value. 
His  comparisons  were  as  follows  : 

TABLE. 


Wolpert. 

Exact  Method. 

f  Bad  =  i  to  2  parts  CO2 

per  1,000. 

1.8  parts  per  1,000. 

}  ::     ::    ::    :: 

.< 

i  .858  parts  per  1,000. 
2.319     " 
1.370 

j  Very  bad  =  2  to  4  parts 

CO  8  per  1,000. 

1.630 
1.750     " 

(     "       M      "      " 

1.583     " 

f  Pure  =  0.5  to  0.7  parts  COa  per  1,000. 


Passable  =  0.7  to  i.o  parts  CO2  per  1,000. 


0.664     " 
0.837     " 
0.596 
0.919 
1.056 

i. 080     " 
i . 600     ' ' 

1.518     " 


Of  the  "  ready  "  or  minimetric  methods  for  the  determination  of 
carbonic  acid  in  the  air,  that  of  Lunge-Zeckendorf  recommends  itself 
by  reason  of  its  simplicity  and  relative  degree  of  accuracy.  The  results 
obtained  by  this  method,  as  can  be  said  of  all  "ready  methods,"  are 
not  absolutely  exact,  but  they  approximate  sufficiently  to  make  the 
method  of  practical  utility.  The  best  results  are  obtained  by  this 
method  when  the  proportion  of  carbonic  acid  is  not  less  than  i  part 
per  thousand.  For  smaller  amounts  than  this,  analysis  by  this  method 
requires  too  much  time. 

The  analysis  is  made  by  the  use  of  a  solution  of  sodium  carbonate 
with  phenolphthalein  as  indicator. 

The  solution  is:  Desiccated  sodium  carbonate,  5.3  grams;  dis- 
tilled water,  1,000  c.c. 

When  the  soda  is  dissolved  one  gram  of  phenolphthalein  in  sub- 
stance is  to  be  added.  The  distilled  water  should. have  been  boiled 
and  quickly  cooled  just  before  making  the  solution,  and  the  solution 
should  be  kept  in  a  tightly-stoppered  bottle. 


MINIMETRIC    METHOD. 


181 


When  the  analysis  is  to  be  made,  2  c.c.  of  the  above  solution  are  to  be 
added  to  100  c.c.  of  boiled  and  cooled  distilled  water,  and  of  this  10  c.c. 
are  employed  in  the  apparatus  shown  in  Fig.  18.  This  apparatus,  as 
the  figure  shows,  consists  of  a  flask  of  about  125  c.c.  capacity  provided 
with  a  rubber  stopper,  through  which  pass  two  glass  tubes.  One  of 
these  tubes  passes  to  the  bottom  of  the  flask,  the  other  is  cut  off  flush 
with  the  under  surface  of  the  stopper.  The  tube  passing  to  the  bottom 
of  the  flask  is  connected  by  a  rubber  tube  with  a  rubber  bulb  of  70  c.c. 
capacity,  which  serves  to  force  the  air  under  consideration  through  the 
test  fluid  in  the  flask.  Before  placing  the  test  solution  in  the  flask  all 
air  should  be  expelled  from  it  and  replaced  by  the  air  to  be  analyzed 


FIG.  i  s. 


by  pressing  the  bulb  between  the  thumb  and  index  finger  several  times. 
When  this  is  done  10  c.c.  of  the  diluted  stock  solution  (2  c.c.  to  100  c.c. 
of  distilled  water,  which  has  been  boiled  and  cooled)  are  placed  in  the 
flask,  the  stopper  quickly  replaced,  and  the  apparatus  is  ready  for 
use. 

The  air  to  be  tested  is  then  forced  through  the  solution  by  pressing 
the  bulb  between  the  thumb  and  index  finger  once,  after  which  the 
rubber  tube  is  pressed  between  the  fingers  and  the  flask  shaken  for  one 
minute,  care  being  given  that  the  fluid  does  not  escape  through  the 
glass  tubes.  If  no  change  of  color  occurs,  the  rubber  bulb  is  refilled 
and  pressed  and  in  this  way  air  is  forced  through  the  solution  until  the 
red  color  of  the  solution  disappears.  From  the  number  of  times  the- 


182  MINIMETRIC    METHOD. 

bulb  is  filled  and  its  contents  forced  through  the  fluid,  the  pro- 
portion of  carbonic  acid  in  the  air  is  determined  by  the  following 
table  : 

Disappearance  of  color  with  48  compressions  of  the  bulb  =  0.3  CO 8  in  i  ,000  air. 

as         "         "         "04 

27          "          "          "         0.5        "        lf 

21  '•  "  "  0.6 

17  '  "  "  0.7 

13  "  "  "  0.8 

10  "  "  "  0.9 

9  "  "  "  i.o 

8  "  "  "  1.2 

7  "  "  1.4 

6  ,.  „  ,,  I>5          „ 

5  "  "  "  1.8 

4  "  2.1 

3  "  "  "  2.5 

<«  "  "  2  "  "  "  3.0  " 

This  process  has  been  repeated,  and  parallel  comparisons  made 
with  Pettenkofer's  method  by  Fuchs,  who  found  that  the  very  dilute 
solution  employed  by  Lunge-Zeckendorf,  when  used  for  very  impure 
air,  gave  irregular  results,  and  decided  from  the  result  of  his  compari- 
sons that  more  exact  and  regular  results  could  be  obtained  where 
4  c.c.  of  the  stock  solution,  instead  of  2  c.c.,  were  added  to  100  c.c. 
of  distilled  water,  and  this  employed  in  the  flask  as  test  fluid. 
He  found  : 

Disappearance  of  color  with  16  compressions  of  bulb=i.2  Co2  in  1,000  air. 

8  "  '•  2.0  " 

"  7  "  "  2.2  " 

6  "  "  2.5  " 

..  5  ..  3-0  .< 

-       4  3-6     " 

"       3  4.2     " 

il         2  4.9       " 

As  a  result  of  a  critical  review  and  comparison  of  the  minimetric 
methods  in  vogue  for  the  approximate  determination  of  the  proportion 
of  carbonic  acid  in  the  air,  Bitter  (Zeitschr.  f.  Hygiene,  Bd.  IX.,  1890), 
concludes  that  the  method  of  Lunge-Zeckendorf  gives  by  far  the  most 
accurate  results,  and  for  hygienic  purposes  is  to  be  recommended 
above  all  the  others,  not  only  because  of  its  accuracy,  but  also  because 
of  its  convenience.  The  result  of  his  analyses  by  this  method,  as  com- 


PETTENKOFER S    METHOD. 


183 


pared  with  analyses  of  the  same  air  by  an  exact  modification  of  the 
Pettenkofer  method,  will  be  seen  in  the  accompanying  table. 


TABLE. 


Experiment. 

Lunge's  Method,  CO2  in 
10,000  Air. 

Exact  Method,  CO,  in 
10,000  Air. 

I 

5-96 

660 

2 

16.00 

15.50 

3 

13.70 

13.50 

4 

10.56 

H.I5 

5 

9.19 

9.OO 

6 

10.56 

IO.OO 

7 

I7-50 

21.00 

8 

3.65 

5-10 

As  has  been  stated,  these  ready  tests  cannot  be  considered  abso- 
lutely accurate,  so  that,  where  accuracy  is  desired,  methods  requiring 
acquaintance  with  chemical  manipulations  and  the  use  of  a  chemical 
laboratory  must  be  employed.  Of  these  more  accurate  methods,  the 
one  most  commonly  employed  is  that  of  von  Pettenkofer. 

This  method  has  for  its  basis  the  fact  that  if  one  brings  air  con- 
taining carbonic  acid  in  combination  with  barium  hydroxide  in  solu- 
tion a  combination  between  the  barium  and  the  carbonic  acid  imme- 
diately takes  place,  and  insoluble  barium  carbonate  is  precipitated, 
expressed  thus: 


2H2O. 


Ba(OH2)  +  H2CO3  =  BaCO3 

If  now  the  barium  solution  be  of  constant  strength  and  we  have 
some  reagent  by  means  of  which  this  strength  may  be  determined  be- 
fore and  after  the  barium  water  has  been  exposed  to  the  carbonic  acid 
it  is  very  easy  to  determine  what  amount  of  carbonic  acid  was  present 
from  the  amount  of  barium  which  has  been  taken  for  the  solution  as 
insoluble  carbonate. 

For  this  purpose  a  solution  of  oxalic  acid  of  definite  strength  is 
employed.  Oxalic  acid  has  exactly  the  same  effect  upon  barium  water 
as  carbonic  acid,  and  in  solutions  of  proper  strength  will  be  equiva- 
lent to  a  definite  amount  of  carbonic  acid.  One  determines,  therefore, 
the  amount  of  oxalic  acid  solution  necessary  to  exactly  neutralize  a 
given  amount  of  the  barium  solution.  The  same  amount  of  barium 
solution  is  now  shaken  with  air  containing  carbonic  acid  and  after  the 
insoluble  barium  carbonate  has  settled  to  the  bottom  we  again  deter- 


184  v.  PETTENKOFER'S  METHOD. 

mine  the  amount  of  the  oxalic  acid  solution  necessary  to  saturate  the 
remaining  barium  hydroxide  in  the  clear  supernatant  fluid. 

By  subtracting  the  amount  of  oxalic  acid  required  after  the 
barium  hydroxide  solution  has  been  exposed  to  the  carbonic  acid  from 
that  required  before  the  exposure,  it  will  be  easy  to  determine  from 
the  difference  the  amount  of  carbonic  acid  which  was  present  in  the 
air  under  consideration. 

SOLUTIONS    REQUIRED. 

Oxalic  Acid  Solution. — As  stated  above,  if  carbonic  acid  is  brought 
in  contact  with  barium  water,  barium  carbonate  is  precipitated  accord- 
ing to  this  formula: 

Ba(OH2)  +  H2CO3  =  BaCO3  +  2H2O. 

If  now  we  substitute  for  the  carbonic  acid  a  body  which  has  the 
same  action  upon  barium  hydroxide,  oxalic  acid  for  example,  we  shall 
have  this  reaction: 

Ba(OH2)  -f  C2H2  O4  =  Ba  C2O4  +  2H2O. 

We  see,  therefore,  that  with  each  molecule  of  barium  hydroxide 
the  same  chemical  reaction  takes  place  with  a  molecule  of  oxalic  acid 
as  with  a  molecule  of  carbonic  acid.  In  other  words,  a  molecule  of 
oxalic  acid  is  chemically  equivalent  to  a  molecule  of  carbonic  acid. 

Now,  since  the  molecular  weight  of  carbonic  acid  (CO2)  is  44, 

C    =  12 
02  =Jf 

44  molecular  weight, 

and  that  of  oxalic  acid  (C2H2O4)  -f-  2H2O  is  I26, 

C2  =  24 
H2  =  4 
04  =_64 

92  -f  2H2O  =126  molecular  weight, 

the  2H2O  being  water  of  crystallization,  we  see  that  by  weight  126 
parts  of  oxalic  acid  have  the  same  chemical  action  as  44  parts  of  car- 
bonic acid — that  is,  126  parts  by  weight  of  the  one  will  neutralize 
exactly  the  same  amount  of  barium  hydroxide  as  will  44  parts  by 
weight  of  the  other. 

Knowing  this  we  make  a  solution  of  oxalic  acid  of  such  strength 
that  each  cubic  centimeter  shall  represent  a  definite  amount  of  car- 
bonic acid.  This  being  determined  we  may  then  calculate  the  amount 
of  CO2  which  was  present  in  the  air  from  the  difference  between  the 


v.  PETTENKOFER'S  METHOD.  185 

amount  of  the  oxalic  acid  solution  necessary  to  neutralize  a  given 
amount  of  our  barium  water  before  the  exposure  to  CO2  and  the 
amount  needed  after  the  exposure.  For  example:  Suppose  25  cubic 
centimeters  of  one  barium  solution  before  exposure  to  the  carbonic 
acid  were  exactly  neutralized  by  25  c.c.  of  an  oxalic  acid  solution  each 
cubic  centimeter  of  which  represented  0.25  c.c.  of  CO2;  after  exposure 
to  the  carbonic  acid  only  20  c.c.  of  the  oxalic  acid  solution  were  needed 
we  see  then  that  the  amount  of  CO2  which  has  combined  with  barium  is 
represented  by  5  c.c.  (25  c.c. — 20  c.c.)  of  our  oxalic  acid.  As  T  c.c.  of 
the  oxalic  acid  is  equivalent  to  0.25  c.c.  CO2,  5  c.c.  will  equal  1.25  c.c. 
CO2;  in  other  words,  1.25  c.c.  of  CO2  have  combined  with  the  barium. 

A  solution  of  oxalic  acid  of  such  strength  that  i  c.c.  represents 
exactly  0.25  c.c.  of  carbonic  acid  contains  1.405  grams  oxalic  acid  to 
the  litre  of  distilled  water,  as  will  be  now  shown. 

We  saw  that  126  parts  or  milligrams  of  oxalic  acid  are  equivalent 
to  44  parts  or  milligrams  of  carbonic  acid;  i  milligram  of  carbonic 
acid  at  o°  C.  measures  in  volume  exactly  0.5084  cubic  centimeters, 
760  m.m.  pressure,  hence  44  milligrams  have  a  volume  of  22.3676  c.c. 
Our  solution  of  oxalic  acid  is  to  be  of  such  strength  that  i  c.c.  will  be 
equivalent  to  0.25  c.c.  carbonic  acid.  Therefore,  if  127  nigs,  oxalic 
acid  are  equivalent  to  22.3676  c.c.  CO2,  x  milligrams  of  oxalic  will 
equal  0.25  c.c.  CO2  —  126  :  22.3676  =  x  :  0.25  x  =  1.405  mgs.  oxalic 
acid. 

If,  therefore,  we  dissolve  1.405  grams  of  oxalic  acid  in  a  litre  of 
distilled  water,  i  c.c.  of  the  solution  will  contain  1.405  mgs.  and  will 
be  equivalent  to  0.25  c.c.  of  CO2. 

In  making  the  solution  it  is  necessary  that  chemically  pure  crystals 
of  oxalic  acid  be  used;  that  they  be  dried  between  folds  of  filter  paper 
at  even  temperature  for  several  hours  before  weighing;  that  the  solu- 
tion be  made  in  a  measuring  flask  of  exactly  i  litre  capacity,  and  that 
the  solution  be  kept  in  a  black  bottle  with  well-fitting,  ground-glass 
stopper. 

Barium  Solution. — The  barium  solution  is  made  by  dissolving 
pure  barium  hydroxide  Ba(OH2)  in  distilled  water.  It  should  be  of 
such  strength  that  25  c.c.  of  it  are  neutralized  by  about  25  c.c.  of  the 
oxalic  acid  solution.  For  a  solution  of  this  strength  3.5  grams  of  pure 
barium  hydroxide  are  dissolved  in  a  litre  of  distilled  water.  Since  the 
most  of  the  samples  of  barium  hydroxide  contain  small  amounts  of  the 
hydroxides  of  the  alkalies,  potassium  and  sodium,  it  is  well  to  add  to 
each  litre  of  the  above  solution  0.2  gram  of  barium  chloride  in  order 
to  remove  these  foreign  hydroxides. 


i86 


V.    PETTENKOFER  S   METHOD. 


The  barium  solution  must  be  kept  in  a  flask  so  arranged  as  to 
prevent  access  of  carbonic  acid  to  it  from  without,  otherwise  its 
strength  will  be  constantly  diminished  by  the  action  of  this  gas.  Such 
an  arrangement  is  represented  in  Fig.  19. 

Indication.  —  The  solution  employed  to  indicate  the  exact  point  at 
which  neutralization  is  accomplished  is  either  one  of  rosolic  acid  or 
phenolphthalein. 

If  the  former,  it  is  made  by  dissolving  0.5  gram  of  rosolic  acid  in 
100  c.c.  of  80  per  cent,  alcohol. 

In  an  alkaline  medium  a  few  (5)  drops  of  this  solution  give  a  dis- 
tinct rose  color,  which  instantly  disappears  with  the  least  trace  of 
acidity. 

If  the  latter  is  selected,  3  grams  of  phenolphthalein  are  to  be 
dissolved  in  100  c.c.  of  alcohol.  This  solution  is  colorless,  but  in 
alkaline  solutions  becomes  distinctly  red  in  color. 


FIG.  19. 

A ,  flask  containing  the  barium  water. 

B,  glass  syphon  for  drawing  off  the  solution. 

C,  rubber  tube,  closed  by  pinch  cock,  into  which  the  tip  of  pipette  may  be 

inserted  for  drawing  off  the  solution. 

Z>,  absorption  bottle  containing  broken  pumice  stone  saturated  with  strong 
solution  of  caustic  soda.  It  robs  the  air  passing  into  the  flask  of  its  car- 
bonic acid. 

Method  of  Performing  the  Analyses. — When  the  solutions  have  been 
prepared  the  exact  volume  of  the  flask  in  which  the  sample  of  air  is  to 
be  collected  must  be  determined.  This  is  done  as  follows  : 

At  15°  C.  the  weight  of  distilled  water  expressed  in  grams  will  be 
equal  to  its  volume  expressed  in  cubic  centimeters.  If,  therefore,  we 


\ 


v.  PETTENKOFER'S  METHOD.  187 

fill  a  large  bottle,  which  should  be  of  about  5  litres  capacity  "struck 
measure,"  with  distilled  water  at  this  temperature  and  weigh  it  and 
then,  after  emptying  and  drying  weigh  it  again,  the  difference  between 
the  two  weights  will  express  the  capacity  in  cubic  centimeters.  This, 
when  once  determined,  may  be  written  upon  the  bottle  and  thus 
obviate  the  necessity  of  repeating  this  part  of  the  operation  when  the 
same  bottle  is  used  in  further  analyses.  For  example  :  Flask  filled 
with  distilled  water  at  15°  C.,  weighs  6,520  grams  ;  flask  empty  and  per- 
fectly dry,  1,020  grams;  contents  of  flask  at  15°  C.,  weigh  =  5,500 
grams,  or  are  equivalent  to  5,500  c.c.  When  this  is  determined  the 
sample  of  air  may  be  collected  in  the  flask. 

For  this  the  flask  is  closed  with  a  rubber  cap  (not  a  stopper)  and 
placed  at  the  point  at  which  the  collection  is  to  be  made,  where  it  re- 
,  mains  for  20  to  30  minutes,  until  it  has  taken  on  the  temperature  of  the 
air.  The  temperature  of  the  air  we  find  to  be  20°  C.  The  barometric 
pressure,  reduced  to  o°  C  is  720  m.m.  The  volume  of  air  contained  in 
our  flask  under  this  temperature  and  pressure  will  be  found  to  be  less 
than  5,500  c.c.m.  when  reduced  to  normal  conditions  of  o°  C  and  760 
m.m.  pressure.  This  reduction  to  normal  conditions  of  temperature  and 
pressure  is  necessary  because  the'volume  of  CO2,  which  will  be  calcu- 
lated from  our  analysis  of  the  barium  water,  is  expressed  in  these 
terms,  and  the  conditions  in  both  cases  must  be  alike  in  order  to  com- 
pare them. 

Another  correction  to  be  made  in  the  volume  of  our  flask  is  for 
the  100  c.c.m.  cf  barium  water,  which  must  be  employed  to  absorb  the 
CO2  in  the  sample  of  air  which  will  be  collected  in  the  flask.  This 
100  c.c.  must  therefore  be  subtracted.  We  have  then,  5,500—100  = 
5,400  c.c.m.,  as  the  volume  of  our  flask  under  the  observed  conditions 
of  20°  C.  temperature  and  720  m.m.  barometric  pressure. 

Reducing  then  by  aid  of  the  formula  given  in  the  chapter  on 
physical  properties  of  the  air,  we  have 

v  -  P 


_ 
760  (i  +  (0.00366x0 

substituting  the  figures 

V=  __  5,4°°X7*o         _=  4,766.6  c.c.m. 
760  (i  +  (o.  00366  x  20) 

Under  normal  conditions,  then,  the  volume  of  air  contained  in  the  air 
flask  measures  4,766.6  c.c.m. 


i88  v.  PETTENKOFER'S  METHOD. 

The  cap  is  now  removed  from  the  flask  and  all  the  air  is  expelled 
from  the  bottle,  and  is  substituted  by  the  air  to  be  analyzed  by  from 
50  to  75  compressions  of  an  average  size  bellows.  To  the  nozzje  of  the 
bellows  a  rubber  tube  must  be  attached  in  order  that  the  air  may  be 
introduced  at  the  bottom  of  the  flask. 

The  cap  is  now  replaced  and  by  means  of  an  accurate  pipette  of 
100  c.c.m.  capacity  this  amount  of  barium  water  is  introduced  into  the 
flask  by  gently  raising  one  corner  of  the  rubber  cap  and  inserting  the 
nozzle  of  the  pipette  as  deep  down  into  the  flask  as  possible.  After 
very  gently  agitating  the  flask,  being  careful  that  the  barium  water 
does  not  touch  the  rubber  cap,  for  20  minutes,  all  the  CO2  in  the  air 
in  the  flask  will  have  been  absorbed  by  the  barium.  The  100  c.c.  of 
barium  water  is  now  poured  off  through  a  funnel  into  a  smaller  bottle 
of  about  125  c.c.  capacity,  which  is  to  be  tightly  closed  with  a  ground- 
glass  stopper,  and  allowed  to  stand  for  about  three  hours,  after  which 
time  all  the  barium  carbonate  shall  have  settled  to  the  bottom,  and  the 
supernatant  fluid  will  be  quite  clear.  In  the  mean  time  we  determine 
exactly  the  relation  between  our  stock  barium  water  and  our  standard 
oxalic  acid  solution.  For  this  purpose  exactly  25  c.c.m.  of  the  barium 
solution  is  pipetted  off  from  the  flask  containing  the  supply  stock  into 
a  100  c.c.  Florence  flask,  and  to  this  five  drops  of  our  indicator  solu- 
tion is  added.  If  the  rosolic  acid  solution  is  employed  the  whole 
takes  on  a  distinct  rose  color.  We  now  allow  the  oxalic  acid  to  flow 
into  the  flask  from  an  accurate  burette,  and  note  carefully  the  exact 
instant  at  which  the  rose  color  disappears.  By  making  two  of  these 
determinations  and  taking  the  mean  of  them,  providing  they  do  not 
differ  more  than  0.2  c.c.  the  one  from  the  other,  we  get  the  exact 
amount  of  the  oxalic  acid  necessary  to  neutralize  25  c.c.  of  our  barium 
solution  before  exposure  to  the  CO2. 

From  the  small  bottle  containing  the  100  c.c.  of  barium  water 
which  has  been  exposed  to  the  CO3,  two  samples  of  25  c.c.  each  are 
now  taken  and  treated  in  exactly  the  same  way.  It  will  be  found  that 
less  of  the  oxalic  solution  will  be  required  than  was  needed  to  neu- 
tralize the  same  amount  of  the  barium  water  before  its  exposure  to  the 
CO2.  Some  of  the  barium  has  therefore  been  thrown  down  as  insolu- 
ble carbonate.  Now,  since  our  oxalic  acid  solution  is  so  made  that 
each  cubic  centimeter  represents  a  definite  volume  of  CO2,  it  is  easy 
to  calculate  the  amount  of  CO2  which  has  combined  with  the  barium 
in  the  100  c.c.  of  barium  water  by  multiplying  the  difference  between 
the  two  titrations  by  0.25,  which  is  the  value  of  each  cubic  centimeter 
of  our  oxalic  acid  expressed  in  terms  of  carbonic  acid  by  volume,  and 


v.  PETTENKOFER'S  METHOD.  189 

this  by  4  to  find  the  amount  for  the  whole  100  c.c.,  since  only  one- 
quarter  of  the  whole  amount  was  employed  in  the  titration. 

Example: — 

25  c.c.  barium  water  before  exposure  to  CO2  =  24.8  c.c.  oxalic  acid. 

25  c.c.  "  "  after  "  "  "  =•  23.3  c.c.  "  " 

Difference  for  25  c.c.  ='  1.5  c.c.  "  " 
Difference  for  100  c.c.  =  6.0  c.c.  "  " 

One  cubic  centimeter  of  our  oxalic  acid  solution  is  equivalent  to 
0.25  c.c.  carbonic  acid,  therefore  6.0  c.c.  will  equal  0.25  x  6  =  1.5  c.c. 
carbonic  acid  at  o°  C.  and  760  m.m.  pressure,  which  was  present  in 
4,766.6  c.c.m.  air  under  the  same  conditions. 

The  relative  amount  of  carbonic  acid  present  in  air  is  for  conven- 
ience expressed  in  parts  in  10,000,  hence 

4,766.6    :    1.5  =:  10,000    :   x. 
x    =          — ~ —   =  3.15  parts  of  CO2   in   10,000  parts  of  the  air 

analyzed. 

This  is  the  method  commonly  employed  for  accurate  carbonic  acid 
analyses.  It  requires,  however,  some  acquaintance  with  chemical 
methods  of  manipulation,  and  to  those  who  are  unpracticed  in  such 
work  a  few  weeks'  instruction  in  a  properly  equipped  laboratory  is 
recommended. 

Apparatus  and  solutions  required  for  Pettenkofer's  CO2  method: 
To   summarize   t>e   apparatus    and   solutions   required    for   this 
analysis  : 

(1)  About  4  litres  of  barium  solution  in  such  a  flask  as  is  shown 

C  barium  hydroxide,  3.5  grams  ; 

in  Fig.  76.     Strength  of  solution  =  -J  barium  chloride,  0.2  grams  ; 

(  dist.  water,  1,000  c.c. 

(2)  Oxalic  acid  solution,  containing   1.405  grams  of  chemically 
pure  oxalic  acid  crystals  to  the  litre. 

(3)  Rosolic  acid  solution,  0.5  grams  rosolic  acid  to  100  c.c.  of  80 
per  cent,  alcohol. 

(4)  One  100  c.c.  pipette,  with  long  nozzle. 

(5)  One  25  c.c.  pipette. 

(6)  One  50  c.c.  burette,  divided  into  o.i  c.c. 

(7)  One  bellows,  with  rubber  tube  about   2  feet  long  attached  to 
nozzle. 

(8)  One  large  flask  of  about  5  litres  capacity  with  well  fitting 
rubber  cap. 


190  V.    PETTENKOFER  S    METHOD. 

(9)  One  small  bottle  of  about  125  c.c.  capacity,  the  stopper  to  be 
of  glass  and  well  fitting. 

(10)  Two  100  c.c.  Florence  or  Ehrlenmeyer  flasks, 
(n)  One  small  funnel. 

(12)  One  accurate  centigrade  thermometer. 

(13)  A  barometer. 

The  alterations  in  volume  expressed  by  such  a  small  volume  of  air, 
as  we  supply,  through  variations  in  barometric  pressure,  are  so  slight  that 
this  factor  may  be  omitted  where  the  rise  and  fall  of  the  mercurial  column 
does  not  exceed  10  m.m.  above  or  below  the  normal  point  (760  m.m.) 

In  collecting  the  air  to  be  analyzed,  care  must  be  had  that  a  fair 
sample  is  obtained.  That  is,  there  should  be  no  one  around  the  im- 
mediate neighborhood  of  the  bellows  other  than  the  manipulator,  and 
he,  too,  should  take  care  that  none  of  his  own  expired  air  is  pumped 
directly  into  the  flask. 

Where  it  is  desirable  to  -have  the  analysis  extend  over  a  longer 
period  of  time,  for  the  purpose  of  determining  the  mean  proportion 
of  CO2  in  the  air  during  this  time,  or  where  the  air  to  be  analyzed  is 
in  such  a  place  that  one  cannot  conveniently  use  the  method  above  de- 
scribed, Pettenkofer  recommends  the  aspiration  of  the  air  through 
baryta  water  contained  in  tubes  of  the  form  seen  in  Fig.  20.  The  same 
solutions  are  employed,  and  the  method  of  calculating  the  results  is  the 
same,  the  only  difference  being  that  instead  of  collecting  the  sample 
of  air  in  a  flask  and  exposing  it  to  baryta  water  in  this  flask,  it  is  drawn 
through  the  baryta  water  in  a  tube.  This  method  finds  applica- 
tion in  the  study  of  ground  air,  the  air  of  wells  and  the  air  of  closed 
spaces  with  small  openings. 

In  this  method  the  tubes  are  arranged  as  shown  in  Fig.  20. 
and  the  air  is  aspirated  through  them  in  a  slow  stream  so  that  rt 
passes  through  the  solution  in  single  bubbles.  Usually  all  carbonic 
acid  is  absorbed  in  the  first  tube,  but  to  prevent  error  the  second  tube 
is  added  in  order  to  check  any  of  the  gas  that  might  have  passed  the 
first  tube  unabsorbed. 

In  practice  the  air  analyzed  by  this  method  is  commonly  supposed 
to  be  richer  in  CO2  than  the  free  atmosphere,  so  that  a  stronger  baryta 
solution  (10  grams  BaOH2  and  0.4  gram  BaCl2  to  the  litre)  is  employed; 
likewise  the  oxalic  acid  solution  may  be  made  so  that  each  cubic  centi- 
meter will  be  equivalent  to  0.5  c.c.  of  carbonic  acid  (2.810  grams  oxalic 
acid  to  1,000  c.c.  water).  After  the  desired  amount  of  air  has  been 
slowly  aspirated  through  the  solution  the  tubes  are  quickly  emptied 
into  bottles  in  exactly  the  same  way  as  when  the  flask  method  is  em- 


CARBONIC    ACID    DETERMINATION.  191 

ployed,  and  after  standing  for  three  or  four  hours  the  supernatant 
clear  portion  of  the  solution  is  pipetted  off  and  titrated  with  the  oxalic 
acid  solution.  The  difference  between  the  titration  of  the  baryta 
water  before  and  after  the  passage  of  the  air  through  it,  expressed  in 
cubic  centimeters  of  oxalic  acid,  is  easily  converted  into  terms  of  car- 
bonic acid  (i  c.c.  oxalic  acid  of  the  stronger  solution  =  0.5  c.c.  car- 
bonic acid)  and  from  this  may  readily  be  calculated  the  proportion  of 
carbonic  acid  per  10,000  parts  air  by  the  proportion: 

a  parts  air  aspirated  :  b  parts  CO,  absorbed  =  10,000  air  :  x  CO2. 


\ 


FIG.  20. 


In  regard  to  the  estimation  of  carbonic  acid  in  the  air  by  the 
barium  method,  Smith  (Veterinary  Journal  and  Annals  of  Comparative 
Pathology,  1886,  Vol.  22,  p.  85,)  makes  the  following  observations: 
If  ammonia  is  present  in  any  appreciable  amount,  the  results  of  the 
carbonic  acid  analyses  by  baryta  water  are  unreliable  if  made  close  to 
the  ground.  The  ammonia  affects  the  sensitiveness  of  the  baryta 
solution  to  which  the  air  is  exposed,  and  makes  it  appear  to  be  purer 
than  it  really  is.  To  avoid  this  fallacy,  air  must  be  collected  from  at 
least  6  feet  above  the  ground. 

Another  method  for  the  estimation  of  this  gas  in  the  air,  which  is 
said  to  be  reliable  and  easy  of  performance,  is  that  of  Szydlowski  (St. 


192 


SZYDLOWSKl'S    METHOD. 


Petersburger  Medicinische  Wochenschrift,  1880,  No.  23).  It  is  as 
follows  : 

The  apparatus  consists  of  two  thick-walled  glass  vessels  A  and  B, 
which  communicate  the  one  with  the  other  through  the  thick-walled 
glass  tube  C,  which  has  a  caliber  of  i  m.m.  diameter. 

The  capacity  of  the  vessel  A  from  the  mark  m  to  the  mark  n  is 
exactly  100  c.c.  at  17^°  C. 

The  vessel  B  must  be  larger  than  A.  Its  exact  capacity  is  not 
important. 

On  the  upper  end  of  the  vessel  A  is  a  horizontal  glass  tube  with 
two  tightly-fitting  cocks,/  and  q. 

The  left  extremity  of  this  tube  with  the  cock/  is  connected  by  a 
cjoselv-ntting  rubber  tube  with  the  U-tube  Z>,  which  contains  bits  of 


M 


FIG.  21 — SZYDLOWSKl'S  METHOD. 


pumjce  stone  which  have  been  soaked  in  concentrated  H2SO4.  The 
tube  D  is  for  the  purpose  of  drying  the  air  to  be  analyzed  and  is 
known  therefore  as  the  "  drying  tube." 

The  right  extremity  of  the  horizontal  tube  with  the  cock  q  is  con- 
nected with  the  U-tube  E,  both  arms  of  which  are  filled  with  granular 
soda-lime,  over  the  top  of  which  should  be  placed  a  wad  of  cotton  or 
asbestos,  which  will  prevent  the  dust  from  the  soda-lime  being  carried 
along  in  the  air  current. 

In  the  right  arm  of  the  tube  E  are  two  glass  tubes,  the  one  of 
which  is  to  be  connected  with  the  horizontal  pipette  MN,  which  is  to 
be  divided  into  10*00  c.c. 


SZYDLOWSKl's    MLTHOD.  193 

The  other  tube  connects  with  the  left  arm  of  U-tube  F,  which  arm 
is  also  filled  with  granular  soda-lime.  From  the  left  arm  of  tube  F  is 
also  a  second  vertical  tube  with  glass  cock  v. 

The  right  arm  of  the  tube  F  is  filled  with  granular  calcium  chlo- 
ride. From  the  right  arm  of  tube  F  pass  two  glass  tubes,  the  one  of 
which  connects  with  the  capillary  tube  /,  the  other  with  the  vessel  B. 

Both  arms  of  tube  JS  and  the  left  arm  of  tube  F  absorb  the  carbonic 
acid  of  the  air  under  investigation. 

The  right  arm  of  tube  Stakes  up  the  water-vapor  which  should 
be  formed  when  the  CO2  is  taken  up  by  the  soda-lime. 

The  tubes  E  and  F  are  the  absorption  apparatus. 

The  whole  of  the  apparatus,  except  the  capillary  pipette  MAT  and 
the  capillary  tube  /,  is  made  fast  to  the  board  TS.  At  the  point  o  the 
board  is  swung  on  a  pivot  which  permits  its  motion  in  the  direction 
indicated  by  the  arrows  at  S. 

The  vessel  B  is  to  be  filled  with  pure  dry  mercury,  so  that  if  the 
end  S  of  the  board  be  lowered,  all  the  mercury  will  flow  out  of  the 
vessel  A,  through  the  tube  C  into  B,  and  the  space  from  M  to  N 
(100  c.c.),  will  contain  nothing  but  air. 

If  the  end  ^  of  the  .board  be  raised,  a  reverse  current  of  mercury 
is  started  and  A  will  be  filled  and  B  empted. 

When  the  mercury  has  filled  A,  exactly  up  to  the  mark  J/,  the 
apparatus  is  fixed  in  position. 

In  the  capillary  pipette  MN  is  a  short  mercurial  column  //. 

On  the  end  M  is  a  short  rubber  tube,  which  upon  being  pressed 
between  the  fingers,  serves  to  regulate  the  position  of  the  mercurial 
column  h. 

The  capillary  tube  /  is  divided  exactly  into  division  of  i  m.m. 
apart.  It  is  allowed  to  hang  vertically  through  a  cork  (not  air-tight), 
in  the  vessel  g  which  contains  a  colored,  dilute  caustic  soda  solution. 
The  capillary  tube  is  immersed  in  the  soda  solution,  so  that  its  first 
division  corresponds  with  the  normal  meniscus.  Through  capillarity 
the  fluid  ascends  in  the  capillary  tube.  The  exact  point  to  which  it 
ascends  is  marked  by  a  bit  of  paper  pasted  upon  the  outside  of  the 
vessel  g.  By  this  arrangement  the  ascent  of  the  fluid  in  the  tube  /, 
when  the  carbon  is  absorbed  from  the  air  being  analyzed  can  always 
be  determined  with  exactness. 

All  joints  of  the  apparatus  must  be  made  air-tight  by  the  use  of 
an  alcoholic  solution  of  sealing-wax  or  lac. 

If  from  any  volume  of  dried  air  enclosed  in  an  air-tight  space  the 
carbonic  acid  be  removed  there  results  a  diminution  in  the  pressure. 


194  SZYDLOWSKI  S    METHOD. 

If  the  pressure  is  to  be  kept  constant  then  must  the  volume  be  reduced 
by  exactly  the  same  amount  as  the  volume  of  the  carbonic  acid  which 
has  been  removed. 

If  the  end  S  of  the  board  be  lowered  until  the  mercury  fills  the 
vessel  B  and  the  tube  C  up  to  the  mark  //,  and  the  cocks  p  and  v  be 
closed  then  all  parts  of  the  apparatus  are  filled  with  air,  except  the 
vessel  B  and  the  tube  6".  If  now  the  end  S  of  the  board  be  raised 
then  the  mercury  flows  through  C  into  A  and  drives  the  air  from  A 
before  it  through  the  absorption  apparatus,  where  it  leaves  its  carbonic 
acid,  into  B.  Lower  the  end  6"  of  the  board  and  the  mercury  returns 
to  B  and  the  air  to  A. 

By  repeating  this  several  times  the  air  in  A  eventually  is  free  from 
carbonic  acid.  This  must  be  done  as  a  preliminary  cleansing  of  the 
apparatus  whenever  new  materials  are  employed  and  a  fresh  analysis 
is  to  be  made. 

After  thus  cleansing  the  apparatus,  before  taking  the  sample,  the 
end  »S  of  the  board  is  to  be  raised  until  the  vessel  A  is  filled  with  mer- 
cury exactly  to  the  mark  ///.  The  cock  q  is  now  to  be  closed  and  the 
cocks  /  and  v  are  to  be  opened.  The  end  S  of  the  board  is  now  to  be 
lowered  until  all  the  mercury  flows  out  of  A  into  B  and  fills  B  and  the 
tube  C  exactly  up  to  the  mark  n.  The  vessel  A,  which  from  m  to  ;/  has 
a  capacity  of  exactly  100  c.c  ,  will  now  be  filled  with  the  air  to  be  anal- 
yzed instead  of  mercury.  This  air  is  dried  in  the  tube  Z>,  through 
which  it  must  pass  in  reaching  A.  The  air  which  was  in  B  escapes 
through  the  tube  with  the  cock  v.  One  must  now  bring  the  mercurial 
column  in  the  pipette  MN  exactly  on  the  first  division  at  the  end  M, 
record  the  exact  height  of  the  colored  solution  in  the  capillary  tube  /, 
close  the  cocks  p  and  v  and  open  q,  and  raise  the  end  6*  of  the  board. 
The  air  to  be  analyzed  will  now  be  driven  from  the  vessel  A  through 
the  absorption  apparatus  over  into  the  vessel  B.  Its  CO2  will  be 
taken  up  in  the  absorption  tubes,  and  in  consequence  its  volume  will 
be  diminished  by  an  amount  equivalent  to  the  volume  of  the  CO2  thus 
absorbed.  As  the  air  is  in  a  closed  vessel,  and  its  volume  has  been 
diminished,  its  pressure  will  therefore  be  reduced,  as  may  be  seen  by  a 
rise  of  the  colored  fluid  in  the  capillary  tube  /.  This  rise  of  fluid  com- 
pensates for  the  diminution  in  volume  of  the  air  in  the  apparatus — in 
other  words,  lessens  the  volume  of  the  apparatus  itself.  To  make  this 
lessening  in  volume  of  the  apparatus  fixed,  before  driving  the  air  over 
the  absorption  apparatus  a  second  time — for  all  the  CO2  may  not  have 
been  absorbed  in  the  first  excursion  through  E  and  F — the  mercurial 
column  in  the  pipette  MN  is  moved  along  toward  N  until  the  colored 


SZYDLOWSKI'S    METHOD.  195 

fluid  in  the  tube  /  returns  to  the  normal  level,  as  indicated  by  the  upcer 
edge  of  the  papery. 

The  air  may  now  be  driven  from  A  again  through  the  absorption 
apparatus,  and  if  no  rise  of  the  fluid  in  /occurs,  then  all  the  CO2  has 
been  absorbed. 

One  reads  now  the  exact  number  of  divisions  on  the  pipette  MN '; 
it  was  necessary  to  move  the  mercurial  column  //,  in  order  to  bring  the 
fluid  in  /  to  its  normal  level.  The  result  is  the  volume  of  carbonic  acid 
which  was  contained  in  100  c.c.  of  air — /.  ^.,  the  per  cent,  of  CO2 
present. 

The  mercury  may  now  be  allowed  to  flow  back  into  A  up  to  m, 
and  the  apparatus  is  ready  for  a  second  analysis. 

Precautions. — In  order  that  the  results  may  be  exact,  it  is  desirable 
to  prevent  any  elevation  in  the  temperature  of  the  air  in  the  apparatus 
over  that  of  the  surrounding  air.  It  is  therefore  to  be  recommended 
that  the  observer  avoid  as  much  as  possible  the  handling  of  the  glass 
parts,  and  that  he  should  stand  as  far  from  the  apparatus  as  conven- 
ient. 

If  these  precautions  are  not  observed,  the  air  in  the  apparatus  will 
be  expanded,  by  reason  of  its  elevation  in  temperature,  and  the  result 
will  be  too  small  a  relative  proportion  of  CO2, 

The  readings  must  be  made  from  as  great  a  distance  from  the 
apparatus  and  with  as  much  rapidity  as  is  consistent  with  accuracy. 

In  passing  through  the  tube  D,  the  temperature  of  the  air  is  ele- 
vated by  the  heat  generated  when  the  H2SO4  takes  up  the  water- 
vapor.  It  is  necessary,  therefore,  to  wait  at  least  five  minutes  before  the 
cock/  is  closed  and  the  experiment  begun. 

One  should  not  hasten  to  regulate  the  level  of  the  column  of  fluid 
in  the  tube  /,  nor  the  position  of  the  mercurial  column  in  the  pipette 
MN. 

One  should  wait  a  minute  before  moving  the  mercurial  column  //. 
It  should  then  be  moved  slowly  and  regularly. 

By  following  the  above  directions,  Szydlowski  claims  that  an  analy- 
sis should  not  take  over  20  minutes. 

The  time  may  be  shortened  by  placing  the  whole  apparatus, 
except  the  two  capillary  tubes  MN  and  /,  in  a  large  vessel  of  water  of 
the  same  temperature  as  the  air  of  the  room. 

The  whole  apparatus  should  not  be  larger  than  40  c.m.,  nor  wider 
than  15  c  m.,  nor  higher  than  30  c.m. 

Reiset  (Comptes  Rendus,  Tome  90,  1880,  p.  1,145;  Ann.  d.  Chim. 
e.  d.  Phys.,  Tome  26,  1882,  p.  164)  describes  the  following  apparatus 


196  REISET'S  METHOD. 

as  a  convenient  means  of  determining  the  proportion  of  CO2  in  the 
atmosphere. 

The  apparatus  (Fig.  22)  consists  of  a  flask  F  of  about  500  c  c. 
capacity.  This  flask  has  two  openings,  one  at  J  through  which  the 
tube  T  passes,  and  the  other  at  /'  through  which  tube  /  passes. 

The  tube  T  is  about  50  c.m.  over  all,  and  has  an  inside  diameter 
of  about  40  m.m.  At  the  points  c^  c'  and  c"  in  this  tube  are  three 
platinum  disks  which  fit  in  the  tube  snugly.  They  are  each  perforated 
by  25  holes  of  0.5  m.m.  in  diameter. 

Tubes  /and  //are  filled  with  pumice  stone  saturated  and  corked 
in  concentrated  H2SO4 — at  the  bottom  of  each  of  these  tubes  is  a  bulb 
for  the  reception  of  the  acid  as  it  becomes  diluted  and  increased  in 
volume  by  the  addition  of  water-vapor — this  prevents  the  capillary 
pores  and  spaces  between  the  bits  of  pumice  stone  from  becoming 
clogged  and  thus  prevent  the  free  passage  of  air. 


FIG.  22. 

The  tube  T  is  introduced  into  the  flask  F,  as  shown  in  drawing, 
and  the  joint  between  it  and  the  flask  made  air-tight  by  means  of 
rubber  tubing,  as  shown  at  J. 

At  /'  another  tube  of  much  smaller  diameter,  /,  is  introduced 
through  a  tightly-fitting  rubber  cork. 

The  drying  tube  /  is  now  placed  in  position.  This  drives  the 
air  before  it  passes  into  F. 

The  tube  //  is  for  the  determination  of  the  amount  of  water 
which  has  evaporated  from  the  barium  solution,  which  is  to  be  placed 
in  F)  during  the  experiment. 

Three  hundred  c.c.  of  barium  water  are  placed  in  F  through  the 
opening  O,  the  stopper  at  O  replaced  and  the  end  x  connected  with 
an  aspirator.  A  measured  volume  of  air  is  drawn  through  the  baryta 
water.  After  a  sufficient  amount  has  passed  the  apparatus  is  discon- 
nected from  the  aspirator,  and  the  baryta  water  titrated. 


ADHESION    OF    AIR    SURFACE.  197 

From  the  difference  between  the  titration  of  the  water  before  and 
after  passage  of  the  air  the  amount  of  CO2  is  calculated. 

A  method  of  examining  the  atmosphere  in  mines  that  is  now  be- 
ing used  at  Kolscheid  near  Wachen,  and  which  is  said  to  prove  useful 
and  reliable,  is  as  follows:  A  collecting  gasometer  is  placed  in  the 
chief  ventilating  shaft.  It  is  so  arranged  that  it  becomes  filled  in 
12  hours;  in  this  way  it  is  possible  to  obtain  a  fair  average  sample  of 
the  mine  air.  From  the  air  thus  collected  the  free  carbonic  acid  is 
absorbed  by  caustic  soda  and  its  percentage  by  volume  is  estimated 
by  noting  the  diminution  in  bulk.  The  marsh  gas,  which  is  the  dan- 
gerous element  in  the  atmosphere  of  the  pit — the  so-called  fire  damp 
of  the  miners — is  now  decomposed  by  a  platinum  wire  heated  to  in- 
candescence by  means  of  an  electric  current.  A  further  diminution  in 
bulk  takes  place,  and  this  being  observed,  the  percentage  of  marsh  gas 
present  can  be  calculated. 

It  is  advisable  for  all  architects  to  familiarize  themselves  with  the 
ready  methods  for  the  approximate  estimation  of  carbonic  acid  in  the 
air  and  to  appreciate  the  importance  of  more  exact  analyses  when  the 
results  of  the  ready  tests  suggest  it,  for  it  is  only  in  this  manner  that 
they  can  prove  that  their  buildings  are  properly  ventilated,  or  can  de- 
cide positively  on  the  merits  of  the  dozens  of  patent  ventilating  ap- 
pliances, which  are  fast  becoming  as  much  of  a  nuisance  as  patent 
lightning  rods. 

It  is  true  that  by  measuring  carefully  the  quantity  of  air  entering 
a  room  in  a  given  time,  and  taking  this  result  in  connection  with  the 
position  of  registers,  etc.,  a  person  of  experience  can  form  a  very 
accurate  and  reliable  opinion  as  to  the  character  of  the  ventilation  of 
the  room;  but  as  explained  above,  the  phrase,  "good  ventilation," 
implies  a  thorough  mixing  of  the  foul  air  with  that  which  is  pure,  and 
the  chemical  test  is  the  only  one  which  will  show  whether  this  mixing 
has  been  effected  or  not. 

In  this  connection  attention  should  be  called  to  a  property  of  air, 
which  is  important  in  ventilation  problems,  although  it  is  hardly 
alluded  to  in  books,  and  that  is  its  tendency  to  adhesion  to  surfaces, 
even  when  in  motion. 

The  best  mode  of  illustrating  it  is,  perhaps,  an  experiment  devised 
by  the  late  Prof.  Joseph  Henry.  Upon  a  large,  smooth  table, 
sprinkle  uniformly  some  light  powder,  such  as  powdered  lycopodium. 
In  the  middle  of  the  table  place  a  bell  glass,  mouth  downward.  Then 
with  a  pair  of  bellows  direct  the  current  of  air  from  the  edge  of  the 
table  toward  the  center  of  the  bell  glass.  The  track  of  this  current 


I9#  DETERMINATION    OF    ORGANIC    MATTER. 

will  be  distinctly  marked  in  the  powder,  and  when  it  reaches  the  bell 
glass  you  will  see  it  divide  into  two  parts,  one  passing  on  one  side,  the 
other  on  the  other,  but  both  adhering  to  the  glass  until  they  meet  on 
the  opposite  side,  when  then  they  will  join  and  continue  in  their 
original  direction. 

When  a  current  of  air  is  started  along  a  wall  or  floor,  it  may 
adhere  to  it  for  several  feet,  or  even  yards,  and  in  this  way  we 
may  have  annoying  draughts  at  points  where  we  had  least  expected 
them. 

In  the  Hall  of  the  House  of  Representatives,  at  Washington,  a  few 
years  ago,  a  large  part  of  the  fresh  air  was  brought  in  through  the  risers 
of  the  platforms  upon  which  the  chairs  of  the  members  are  placed. 
This  sheet  of  air,  introduced  under  pressure,  and  in  a  horizontal 
direction,  did  not  diffuse  directly  upward,  as  it  was  intended  to  do, 
but  adhered  to  the  floor,  and  swept  across  the  ankles  of  the  member 
just  in  front.  When  it  had  passed  his  desk  and  reached  the  next  riser, 
it  was  reinforced  by  a  fresh  stratum,  and  the  honorable  member  next 
in  front  received  the  upper  current  on  the  calves  of  his  honorable  legs,, 
while  the  floor  current  swept  his  ankles,  to  his  great  discomfort  and 
dissatisfaction. 

In  like  manner  the  current  from  a  warm-air  register,  placed  in  the 
floor  in  the  corner  of  a  room,  adheres  to  the  sides  of  the  room  and 
passes  directly  upward,  almost  as  if  it  were  in  a  tube.  It  then  streams 
along  the  ceiling  to  an  opening  into  a  foul-air  flue  in  the  opposite  corner, 
and  passes  out  without  disturbing  the  air  in  the  lower  part  of  the 
room. 

In  this  way  it  may  happen  that  a  sufficient  quantity  of  air  may  be 
passing  into  and  out  of  a  room  and  yet  that  the  ventilation  may  be 
extremely  unsatisfactory.  It  is  necessary  to  secure  distribution  as  well 
as  entrance  and  exit. 

For  the  determination  of  organic  matter  in  the  air,  Carnelley  and 
Mackie*  propose  the  following  method  as  a  substitute  for  the  two 
methods  of  Smith  hitherto  employed — viz.:  the  passage  of  a  measured 
volume  of  air  through  potassium  permanganate  solution  of  known 
strength,  after  which  the  loss  experienced  by  the  permanganate  solution, 
expressed  in  volumes  of  oxygen  necessary  to  oxidize  the  organic  matter 
in  the  air  passed  through  it,  is  determined  by  titration;  or  the  passage 
of  air  through  distilled  water,  the  amount  of  albuminoid  thus  added  to 

*  Carnelley  and  Mackie,  "  The  Determination  of  Organic  Matter  in  the  Air, " 
Proc.  Rov.  Soc.,  London,  1886,  No.  41,  p.  238. 


DETERMINATION    OF    ORGANIC    MATTER.  199 

the  water  being  determined  by  the  method  suggested  by  Wanklyn  and 
Chapman  for  water  analysis. 

Both  ot  these  methods  require  much  time,  considerable  apparatus, 
and  are,  according  to  Carnelley  and  Mackie,  open  to  errors  of  greater 
or  less  extent,  depending  upon  ciicumstances. 

The  method  proposed  is  based  upon  the  reduction  of  potas- 
sium permanganate.  It  differs,  however,  from  Smith's  method, 
particularly  in  the  mode  of  determining  the  amount  of  reduction. 
This  consists  in  determining,  cftorimctrically,  by  comparison  with 
a  standard,  the  fractional  bleaching  effected  by  a  known  volume  of 
air. 

Method. — The  solution  of   permanganate   employed    is    of 


[,OOO 

/._      .    normalj  strength,  i  c.c.  of  which  =  0.008  mg.  of  oxygen,  the 

volume  of  which  is,  under  normal  conditions,  0.0000056  litre. 

n 
It  is  usually  kept  of  —  strength,  and  diluted  as  required  for  use, 

about  50  c.c  of  dilute  sulphuric  acid  (1.6)  being  added  to  the  weak 
solution. 

For  the  collection  of  samples  of  air  large,  well-stoppered  bottles 
of  about  3.5  litres  capacity  are  used.  The  jars  are  first  rinsed  out  with 
a  little  standard  permanganate,  and  when  not  in  use  a  little  of  the  solu- 
tion is  always  left  in  them,  so  as  to  insure  complete  freedom  from  any  re- 
ducing substance.  Before  use  the  jars  are  drained,  and  the  sample  of  air 
is  then  collected  by  pumping  out  the  contained  air  with  a  small  bellows 
and  allowing  the  air  to  be  analyzed  to  flow  in;  50  c.c.  of  the  standard 
permanganate  are  next  run  into  the  jar,  which  is  then  tightly  stoppered 
and  well  shaken  for  at  least  five  minutes;  25  c.c.  of  the  permanganate 
are  afterwards  withdrawn  by  a  pipette  and  placed  in  a  glass 
cylinder  holding  about  200  c.c.,  25  c.c.  of  the  standard  solution 
being  placed  in  a  similar  cylinder  for  comparison.  Both  are  now 
diluted  up  to  about  150  c.c.  with  distilled  water,  and  allowed  to 
stand  for  10  minutes,  after  which  the  tints  in  the  two  cylinders 
are  compared.  Standard  solution  is  then  run  from  a  burette  into 
the  cylinder  containing  the  solution,  which  has  been  acted  upon 
by  the  air  under  examination  until  the  solutions  in  the  two  cylinders 
are  of  the  same  intensity  of  color  ;  usually  from  0.5  to  6.  c.c.  are 
required. 

The  amount  of  solution  added  from  the  burette  is  a  measure  for 
the  bleaching  effected  by  the  known  volume  of  air  in  the  flask  on  half 


2OO  DETERMINATION    OF    ORGANIC    MATTFR. 

the  permanganate  employed.  This  multiplied  by  2  gives  the  total 
bleaching. 

The  result  may  be  expressed  either  in  terms  of  the  number  of  c.c, 

of  the-      -  bleached   by   i.  litre   of  air,   or,  as  is  preferred,  by  the 
1,000 

number  of  volumes  of  oxygen  required  to  oxidize  the  organic  matter 
in  1,000,000  volumes  of  air;  e.g.,  25  c.c.  of  a  solution  from  a  3. 5-litre 
jar  in  which  50  c.c.  had  been  used,  required  3  c.c.  of  the  permanganate 
to  bring  it  up  to  the  standard,  or  the  whole  50  c.c.  would  have  required 
3X2=6.  c.c.  This,  then,  represents  the  number  of  c.c.  of  the  standard 
solution  bleached  by  3,500  —  50  =  3,450  c.c.  of  air  ;  consequently 

6 
=  1.74  c.c.  is  bleached  by  T  litre  of  air.      But  i.  c.c.  of  KMnO4  — 

00000056  litre  of  oxygen  .  •.  1.74  c.c.,  KMnO4=o. 0000056 x  1.74  = 
0.0000097  litre  of  oxygen  is  required  to  oxidize  the  organic  matter  in 
i  litre  of  air,  or  9.7  volumes  of  oxygen  to  oxidize  the  organic  matter 
in  1,000,000  volumes  of  air. 

Correction  for  temperature  is  not  considered  necessary,  as  it  falls 
within  the  limits  of  experimental  error.  It  requires  about  20  minutes 
to  collect  the  sample  and  complete  the  analysis.  Scrupulous  cleanli- 
ness is,  of  course,  necessary  in  all  the  operations. 

After  the  examination  of  many  hundreds  of  samples  of  air  by  this 
process  Carnelley  and  Mackie  are  led  to  believe  that  the  results 
obtained  by  it  are  as  accurate  as  possible  in  the  present  state  of  our 
knowledge  upon  the  subject. 

Duplicate  analyses  of  the  same  air  gave  very  concordant 
results. 

The  objections  to  the  method  are: 

(1)  That  it  does  not   directly   estimate  the  organic  matter,    but 
only  measures  the  amount  of  oxygen  required  to  oxidize  either  the 
whole,  or,  more  probably,  only  a  portion  of  it. 

(2)  That  the  permanganate  acts  upon  various  matters  in  the  air 
besides  the  organic  matter,  such    as   sulphuretted  hydrogen,  nitrous 
acid,  sulphurous  acid,  etc. 

(3)  That    the  organic    matter   in   the    air    is   of   various    kinds, 
and   that,   consequently,    the    permanganate   will    most    probably   be 
selective   in    its    action.      Our   knowledge    on   this    point,    however, 
is   so   defective    that    no   definite    conclusion    is   possible    in    regard 
to  it. 

(4)  There  is  no  satisfactory  means  of  checking  the  results,  the 
only  method  being  to  make  duplicate  determinations  of  the  same  air. 


DETERMINATION    OF    ORGANIC    MATTER. 


2OI 


(5)  The   uncertainty  that  the  permanganate  exerts  its  full  action 
in  a  cold  acid  solution  of  such  dilution  as  that  recommended  above. 

This  test,  such  as  it  is,  the  method  stands  extremely  well,  as  will  be 
seen  from  the  results  given  below: 

ORGANIC  MATTER. 


Vols.  of  0  Re- 

quired to  Oxidize 

the  Organic 

Matter  in  1,000  ooo 

Vols.  of  Air. 

., 

c 

o 

j 

• 

•g  s 

£•- 

c 

Mean. 

i!     •"  o> 

0)              V 

~        ci 

Outside  air  (Dundee).  . 

9.0 

12.  0 
IO.O 

8.9 
ii.  5 

10.2 

8-95 
11.75 

IO.  IO 

Immediately  after  rain. 
No  rain  during  day. 
Heavy  rain  with  wind. 

.1  • 

8.6 

8.1 

8.35  Rain  shortly  before. 

(Perth).... 

2.0 

1.6 

i  .  80  Strong  wind  and  rain. 

•« 

2.6     1.5 

i  .  75  'Strong  wind,  rain  at  intervals. 

" 

4-0 

2.0 

2.  20  Storm  shortly  before. 

" 

4.8 

4-6 

4.70  Fine. 

Class-room  (Dundee).  . 
rt      (Perth)... 

10.5 
7.6 

8.8 

7.8 

9.65 
7.70 

Unoccupied.     Just  after  dusting. 
29  present  for  i  hour. 

"        •  «           " 

4-0 

5-0 

4.50 

31 

Small  room     .         .... 

II    0 

114. 

ii  .65 

Unoccupied.     Two  gas  jets  burning  15 

•  V 

•*•  A  •  T" 

minutes. 

«« 

12.9 

13.0 

12.95 

One  person  and  i  gas  jet  20  minutes. 

<4                           «< 

17.2 

17.0 

17.10 

Ditto,  after  i  hour  and  40  minutes. 

«                            11 

20.0 

20.5 

20.25 

Ditto,  on  another  occasion. 

The  method  does  not  give  absolute,  but  only  relative  results. 

The  conclusions  drawn  by  Carnelley  and  Mackieasaresult  of  their 
air  analyses,  were  : 

(i)  That  the  quantity  of  organic  matter  in  the  outside  air  varies 
considerably,  within  certain  limits,  from  day  to  day,  and  from  hour  to 
hour  on  the  same  day. 

It  has  been  found  to  be  somewhat  less  immediately  after  or  during 
rain  or  snow,  thus  : 


Organic  matter  (O  required  per  1,000,000  ) 

vols.  of  air) f 

Carbonic  acid  (per  10,000  vols.  of  air) 


No  RAIN  OR  SNOXV 


No. 
of   Cases. 

Lowest. 

Highest. 

Mean. 

19 

1.6 

15-8 

7-9 

15               2.2 

5-4 

3.86 

202 


DETERMINATION    OF    ORGANIC    MATTER. 


JUST  AFTER  OR  DURING  RAIN 

OR  SNOW 

No. 
of   Cases. 

Lowest. 

Highest. 

Mean. 

Organic  matter  (O  required  per  1,000,000  \ 
vols.  of  air)            .       .                         •  •  •  j 

19 
II 

i.  8 
2.4 

13-3 
5-6 

7-3 
3-95 

Carbonic  acid  (per  10,000  vols.  of  air) 

The  highest  results  of  all  were  obtained  on  foggy  nights — e.g.,  15.7, 
17.0.  High  results  were  also  obtained  during  a  slight  drizzling  rain, 
accompanied  by  mist. 

(2)  A  close  connection  is  observed  between  the  amount  of 
organic  matter  in  the  air  and  the  combustion  of  coal.  It  is  lowest  in 
the  middle  of  the  night,  rather  higher  in  the  morning,  and  considera- 
bly higher  in  the  middle  of  the  day,  and  higher  still  toward  evening, 
alter  which  it  decreases.  Thus  : 


8  P.  M.— 

5  A.  M. 

5  A.  M.- 

ro  A.  M. 

10  A.M.— 
3P.M. 

3  P.M.— 
8PM. 

Organic  matter  (O 
vols.  of  air)  .  .  . 

required  per  1,000,000  } 
\ 

3-9 

4-9 

7-9 

9-1 

Carbonic  acid  per 

10,000  vols.  of  air  

4.1 

2.Q 

3.4 

3   c 

MEANS. 


(3)  A  relation  of  organic  matter  to  carbonic  acid  in  outside  air 
shows,  so  far  as  the  tabulated  results  go,  a  high  carbonic  acid  accom- 
panied by  a  high  organic  matter,  and  vice  versa.  This  is,  however,  by 
no  means  invariable,  and  is,  in  fact,  only  shown  by  the  averages  of 
a  large  number  of  cases.  To  show  this,  all  the  determinations  which  have 
been  made  in  the  outside  air  were  divided  into  four  groups,  according 
to  the  quantity  of  organic  matter  present  and  the  averages  of  the  cor- 
responding carbonic  acid  found,  as  in  the  following  table: 


Vols.  of  O  Required  to  Oxidize  the 
Organic  Matter  in  1,000,000 
Vols.  of  Air. 

Average  Carbonic  Acid  in 
10,000  Vols.  of  Air. 

Number  of 
Determinations. 

o  to    2.5 

2.8 

20 

2-5  to    4.5 

3.o 

20 

4-  5  to    7.0 

3  •  2 

2O 

7.0  to  15.8 

3-7 

20 

EFFECTS    OF    ARTIFICIAL    LIGHTS. 


203 


(4)  The  organic  matter  in  the  outside  air  has  a  far  wider  range 
of  variations  than  the  carbonic  acid.    The  latter  seldom  passes  beyond 
the  limits  of  2  to  6  volumes  in  10,000,  whereas  the  organic  matter  may 
vary  from  amounts  too  small  to  estimate  up  to  that  requiring  as  much 
as  16  volumes  of  oxygen  per  1,000,000  volumes  of  air  for  its  oxidation. 

Its  fluctuations  are  also  more  rapid. 

(5)  The  combustion  of  gas  does  not  appreciably  increase  the 
amount  of  organic  matter  in  the  air. 

EXPERIMENTS  IN  A  ROOM.     PRACTICALLY  AIR-TIGHT. 


COS  per  10,000 
Vols.  of  Air. 

Organic  Matter  (Vols. 
of  C  Required  per 
1,000,000  Vols.  of  Air.) 

Before  gas  was  burnt  

4-  3 

IO.6 

IEach  of  these 

After  gas  had  been  burn-  / 
ing  15  minutes.   ...          \ 

II.  0 

ii.  8 

is  the  mean 
of  two  near- 

After gas  had  been  burn-  i 
ing  30  minutes  f 

14.8 

.1.8 

ly   concord- 
ant   experi- 

j     ments. 

The  combustion  of  gas  may  therefore  be  considered  to  have  been 
too  perfect  to  produce  any  appreciable  effect.  What  result  is  obtained 
may  safely  be  attributed  to  sulphurous  acid  (SO2). 

The  above  applies  to  Dundee  gas,  which  is  considered  excep- 
tionally free  from  sulphur. 

(6)  The  effect  of  burning  oil  lamps  is  much  more  marked  than 
that  of  the  combustion  of  gas. 

This  was  determined  in  the  same  manner  as  were  the  results  in 
the  case  of  gas— in  a  practically  air-tight  room. 

RESULT  OF  BURNING  OIL  LAMPS  IN  A  PRACTICALLY  AIR-TIGHT  ROOM. 

Organic  Matter  (O  Required  per 
1,000,000  Vols.  or  Air.) 

Before  the  burning  of  oil  lamps 8 . 7 1 

After  one  lamp  had  been  burn-  I 

ing  half  an  hour  it  was  found  > 12.3 

to  be  smoking  slightly. 
After  burning  one  hour — lamp 

burning  clear... 14.6 

After  the  first  lamp  had  been^l 

burning    one    and    one-half  i 

hour,  and  a  second  lamp  half  }•    16.7 

an  hour,   the    second    lamp  I 

was  found  smoking  slightly.  ] 
Ditto,    after    first    lamp    had"! 

been  burning  two  hours,  and 

the    second  one  hour,   both  .  ' 

lamps  found  burning  clear .  J 


18.1 


Each  of  these  is 
the  mean  of 
two  nearly 
concordant 
determina- 
tions. 


204 


AMMONIA    IN    THE    AIR. 


In  each  case  the  lamps  were  burning  paraffine  oil  and  were 
turned  on  as  full  as  possible  without  smoking. 

(7)  Respired  air  gives  a  higher  result  than  unrespired  air  at  the 
same  time,  though  much  less  than  was  anticipated. 

Experiments  in  a  small,  air-tight  room  occupied  by  one  person. 
The  person  made  the  experiments  in  the  room  without  opening  the 
door.  During  the  whole  time  a  single  gas  jet  was  burning: 


Outside 

Air. 

After 
co  Minutes. 

After 
30  Minutes. 

After 
60  Minutes. 

After 
100  Minutes. 

(   QQ 

ist  experiment,    ]Q  M 

3-8 
9-5 

ii.  4 
12.9 

14.8 
14.8 

(  CO 
2d   experiment,    1  Q  *| 

.... 

.... 

I3-I 
14-2 

23-5 
15.9 

28.2 
17.0 

(  CO 
3d  experiment,  j  O.M'. 

... 

.... 

17.2 

13.5 

24.1 
15.7 

32.1 
20.3 

Here  it  is  seen  that  the  increase  of  organic  matter  is  not  propor- 
tionate to  the  time;  neither  does  it  increase  with  the  same  rapidity  as 
the  carbonic  acid. 

(8)  An  atmosphere  which  has  been  entirely  at  rest  for  some  time 
is  found  to  contain  less  organic  matter  than  it  previously  did.  This  is 
not  of  necessity  due  to  the  settling  down  of  dust,  but  is  probably  due 
in  part  to  oxidation. 

The  amount  of  carbonic  acid  is  no  certain  index  of  the  quantity  of 
organic  matter  present  in  an  atmosphere.  That  air  in  which  respira- 
tion has  gone  on  for  some  time  gives  invariably  a  higher  result  than 
outside  air  at  or  about  the  same  time  is  all  that  can  be  confidently 
affirmed.  The  statement  that  organic  matter  in  respired  air  increases 
part  passu  with  the  carbonic  acid  may  be  true  for  an  average  of  a  large 
number  of  observations,  but  it  is  not  true  for  individual  cases. 

Ammonia  in  the  Air. — The  presence  of  ammonia  in  the  air  can 
sometimes  be  demonstrated  by  the  change  in  color  that  it  produces 
upon  delicate  litmus  or  curcuma  paper,  by  virtue  of  its  alkaline 
reaction.  A  strip  of  moistened  litmus  or  curcuma  paper  is  clamped 
between  two  perfectly  clean  glass  plates,  in  such  a  way  that  about 
one-half  of  it  projects  beyond  the  borders  .of  the  glasses.  If  am- 
monia is  present  in  unusual  amounts,  the  exposed  end  of  the  papers  will 
be  altered  in  color,  from  red  to  blue  in  the  case  of  litmus,  from  yellow 
to  brown  in  the  case  of  curcuma.  The  bit  of  paper  between  the  glass 


AMMONIA    IN    THK    AIR.  205 

plates  is  not  exposed  to  the  action  of  the  ammonia,  so  that  it  serves  as 
a  standard  with  which  to  compare  the  extent  of  color  change,  which 
will  be  more  rapid  and  greater  in  degree,  as  the  amount  of  ammonia 
present  is  greater. 

A  similar  test  can  be  made  with  logwood  paper.  Bits  of  paper  are 
saturated  in  a  tincture  of  logwood,  and  exposed  in  the  way  just 
described.  If  ammonia  is  present,  the  yellow  color  of  the  paper  takes 
on  a  violet  or  reddish  violet  color. 

For  the  quantitative  analyses  of  the  air  for  ammonia,  experience 
in  chemical  manipulation  is  necessary,  as  the  greatest  care  is  to  be  taken 
in  order  to  exclude  sources  of  error. 

A  method  commonly  employed  for  this  purpose  is  the  aspiration 
of  a  given  volume  of  air  through  a  given  volume  of  a  solution  of  sul- 
phuric acid  of  known  strength.  The  loss  experienced  by  the  acid  solu- 
tion, in  combining  with  the  ammonia  in  the  air,  is  determined  by  titra- 
tion,  and  the  amount  of  ammonia  corresponding  to  the  amount  of  loss 
in  the  acid  solution,  is  found  by  calculation. 

Another  method,  that  devised  by  Remsen,  which  is  perhaps  the 
most  reliable  of  any  of  the  methods  employed  for  this  determination,  is 
the  absorption  of  the  ammonia  from  air  by  aspiration  through  a  layer 
of  pumice  stone,  broken  into  bits  of  about  the  size  of  a  duck  shot. 
When  the  desired  amount  of  air  has  been  drawn  through  the  absorber 
(the  pumice  stone),  the  latter  is  then  mixed  with  a  known  volume  of 
distilled  water,  free  from  ammonia.  By  distillation,  at  first  of  the  mix- 
ture as  it  now  is  with  a  small  proportion  of  sodium  carbonate,  all 
ammonia,  as  such,  is  distilled  over  with  the  water,  and  its  amount 
determined  in  the  distillate  by  nesslerization.  After  this,  by  means  of 
an  alkaline  potassium  permanganate  solution,  the  remaining  organic 
combination,  an  albuminoid  ammonia,  as  it  is  called,  is  decomposed  and 
distilled  over,  and  its  amount  determined  in  the  same  way. 

These  are  processes  that  must  be  practiced  in  order  that  they  may 
be  properly  conducted,  as  there  are  few  analyses  requiring  greater  care 
in  manipulation  than  those  designed  for  the  estimation  of  ammonia  in 
the  air. 

For  the  estimation  of  the  number  of  micro-organisms  contained 
in  a  given  volume  of  air,  quite  a  variety  of  methods  exist.  The  simple 
demonstration  of  their  presence  in  air  without  regard  to  relative  num- 
bers is  a  simple  matter,  requiring  little  or  no  skill  on  the  part  of 
the  operator.  A  slice  of  freshly-cooked  potato,  a  bit  of  moistened 
bread,  or  a  small  portion  of  melted  gelatine,  poured  upon  a  plate,  if 
'exposed  for  a  time  to  the  air  ot  an  inhabited  room,  will  be  marked 


2O6  BACTERIA    IN    THE    AIR. 

after  24  to  36  hours  by  colonies  developing  from  bacteria  that  have 
fallen  upon  it  from  the  air.  For  the  quantitative  estimation,  however, 
the  conditions  must  be  more  carefully  controlled.  A  measured  volume 
of  air  must  be  aspirated  over  or  through  some  medium  that  not  only 
arrests  the  bacteria  that  were  contained  in  it,  but  presents  conditions 
that  will  permit  of  these  bacteria  being  cultivated  in  such  a  way  that 
each  single  bacterium  will  serve  as  a  starter  from  which  a  colony  will 
grow,  and  by  counting  these  colonies,  it  is  then  easy  to  say  how  many 
individual  organisms  were  present  in  the  amount  of  air  employed. 
This,  in  short,  is  the  principle  upon  which  all  of  these  methods  are 
based,  but  it  must  be  borne  in  mind  in  making  these  estimations  that 
there  is  one  condition  that  it  is  difficult,  if  not  impossible,  to  eliminate, 
and  that  is  the  condition  in  which  bacteria  are  usually  found  to  exist  in 
the  air.  As  commonly  found  they  are  located  upon  floating  dust  par- 
ticles, and  may  be  at  times  alone  upon  a  bit  of  dust,  but,  as  is  usually 
the  case,  they  are  deposited  upon  it  in  numbers.  It  is  evident,  there- 
fore, that  in  counting  the  resulting  colonies  as  representing  in  each 
case  the  outgrowth  from  a  single  germ,  there  is  always  the  possibility 
of  error. 

The  methods  commonly  employed  for  this  determination  which 
are  believed  to  give  the  most  reliable  results  are  those  of  Petri  and  its 
modification  by  Sedgwick.  The  former  consists  in  aspirating  the  air 
through  fine  sand,  which  deprives  it  of  all  bacteria.  When  the  desired 
amount  of  air  has  been  drawn  through  the  sand  filter,  the  sand  is 
mixed  with  sterilized  fluid  gelatine,  which  is  then  to  be  poured 
out  upon  a  broad  glass  plate  into  a  very  thin  layer.  As  it 
solidifies,  each  bacterium  is  fixed  in  its  place  in  the  gelatine, 
and  proceeds  to  develop  into  a  colony  of  bacteria.  At  the  end 
of  24  to  36  hours  these  colonies  are  counted  and  as  each  is 
assumed  to  result  from  the  growth  of  a  single  bacterium  this  number  is 
assumed  to  represent  the  number  of  bacteria  in  the  amount  of  air 
drawn  through  the  sand.  In  the  method  of  Sedgwick,  sugar  is  substi- 
tuted for  sand,  because  of  the  insolubility  of  the  latter,  which  frequently 
gives  rise  to  errors,  as  it  is  sometimes  difficult  to  distinguish  between 
a  very  small  sand  granule  and  a  colony  of  bacteria.  Moreover,  the 
apparatus  proposed  by  Sedgwick  prevents,  to  a  large  extent,  con- 
taminations from  without  that  are  not  impossible  during  the  process  of 
pouring  out  the  mixture  of  sand  and  gelatine.  The  sugar,  of  a  definite 
size  grain,  is  placed  in  a  narrow  glass  tube  of  about  2  to  3  m.m.  inside 
diameter  and  about  6  c.m.  in  length ;  the  tube  is  widened  out  at  one  end 
into  a  glass  cylinder  of  about  2  to  3  c.m.  inside  diameter  and  of  about 


BACTERIA    IN    THE    AIR.  207 

6  c.m.  long.  The  whole  tube,  containing  the  sugar  only  in  its  narrow 
end  and  being  plugged  at  both  ends  with  cotton,  is  sterilized  by  heat 
so  as  to  destroy  any  living  bacteria  that  may  be  in  it.  When  sterilized 
the  cotton  plug  is  removed  from  the  large  end  and  the  small  end  is 
connected  with  an  aspirator.  A  definite  amount  of  air  is  drawn  through 
it  and  in  its  passage  through  the  sugar  it  leaves  all  its  bacteria  adherent 
to  the  sugar  granules.  When  the  desired  amount  of  air  has  passed 
through  the  sugar  the  cotton  plug  is  replaced  in  the  large  extremity 
of  the  tube  and  it  is  then  held  in  an  almost  horizontal  position  and 
gently  tapped  against  the  finger  until  all  the  sugar  has  been  caused  to 
pass  from  the  small  into  the  large  part  of  the  glass  cylinder,  taking  its 
bacteria  with  it.  When  this  is  accomplished,  about  10  to  15  cubic 
centimeters  of  sterilized  liquid  gelatine  is  poured  into  the  large  end  of 
the  tube,  the  sugar  dissolves  in  it  and  the  tube  is  then  rolled  in  the 
horizontal  position  upon  ice.  The  low  temperature  causes  the  gelatine 
to  solidify  and  thus  fix  the  bacteria  at  different  parts  upon  the  inner 
walls  of  the  tube.  They  develop  into  colonies  and  can  then  be  counted, 
as  in  the  process  of  Petri  The  advantages  of  this  process  are  the  solu- 
bility of  the  filtering  medium  and  the  diminution  in  the  chances  of 
contamination  by  bacteria  from  sources  other  than  that  under  consid- 
eration during  manipulation. 

This  is  not  the  place  for  a  detailed  description  and  critical 
discussion  of  bacteriological  methods.  What  has  been  said  will  suffice 
to  indicate  the  general  principles  upon  which  these  determinations 
are  based.  For  a  more  minute  description  of  the  methods  employed 
and  the  general  conditions  underlying  bacteriological  manipulations 
special  works  on  the  subject  must  be  consulted. 


CHAPTER    X. 

METHODS    OF     HEATING:     STOVES,    FURNACES,    FIREPLACES,    STEAM    AND 
HOT-WATER    THERMOSTATS. 

IT  is  presumed  that  every  reader  of  this  book  will  admit  that  good 
ventilation  is  a  very  desirable  thing,  and  that  we  should  pay  at  least 
as  much  attention  to  it  as  to  the  ornamentation  of  buildings.  But  we 
must  also  bear  in  mind  another  very  important  fact — viz.,  that  in  cold 
weather  satisfactory  heating  is  even  more  desirable  and  necessary, 
since  without  it  the  better  the  ventilation  the  louder  will  be  the  com- 
plaints. We  may  write  and  talk  as  much  as  we  please  about  the 
horrors  of  foul  air  and  the  importance  of  good  ventilation,  but  we 
shall  never  induce  people  to  consent  to  sit  in  cold  draughts  and  shiver 
for  the  sake  of  pure  air,  and,  in  fact,  we  would  not  do  it  ourselves. 

In  preparing  plans  for  ventilation  we  must,  therefore,  consider 
the  methods  of  heating  to  be  employed  in  cold  weather.  Heat  is  a 
force,  that  is,  a  mode  of  motion  of  the  molecules  of  gaseous,  liquid,  or 
solid  matter,  and  most  of  the  heat  which  is  of  practical  interest  to  us 
in  this  connection  is,  or  has  been,  derived  from  the  rays  of  the  sun. 
Fuel  of  all  kinds  contains  force  stored  up  from  the  sun's  rays  by 
plants,  and  animal  heat  comes  from  the  same  source.  The  production 
of  artificial  heat,  as  it  is  commonly  termed,  for  the  purpose  of  warm- 
ing or  ventilating  a  building  is  usually  effected  by  the  combustion  of 
fuel,  and  we  can  obtain  only  a  certain  limited  amount  of  heat  from  a 
certain  quantity  of  a  particular  kind  of  fuel.  To  obtain  this  fuel  and 
place  it  where  it  is  needed,  and  to  provide  the  necessary  apparatus  for 
its  combustion,  and  for  the  conveyance  and  distribution  of  the  heat 
thus  produced,  requires  labor,  in  other  words,  it  costs  money,  and  this 
cost  varies  greatly  in  different  localities  and  with  different  forms  of 
heating  apparatus.  The  problem  of  the  heating  engineer  is  to  obtain 
in  each  particular  case  satisfactory  results  as  to  temperature  and 
ventilation  with  the  greatest  economy,  and  this  economy  must  be 


HEAT    MEASURES.  209 

. 

studied  both  with  reference  to  the  cost  and  durability  of  the  apparatus 
required  and  the  amount  of  fuel  to  be  supplied.  For  measuring  and 
comparing  quantities  of  heat  a  unit  of  measure  is  required,  and  that 
which  is  most  commonly  used  in  this  country  is  the  amount  of  heat 
required  to  raise  a  pound  of  water  i°  F.,  say  from  32°  F.  to  33°  F. 
The  amount  of  heat  required  to  raise  one  pound  of  water  i  degree 
in  temperature  differs  slightly  for  different  parts  of  the  scale,  and  in 
modern  scientific  calculations,  what  is  known  as  the  British  thermal 
unit,  abbreviated  B.  T.  U.,  is  used,  being  the  amount  required  to  raise 
a  pound  of  water  from  50°  F.  to  51°  F.  The  difference  between  these 
two  thermal  units  need  not  be  considered  in  problems  of  house  heating. 
In  the  metric  system  the  unit  of  heat  is  the  calorie  (in  the  plural 
calories)  being  the  amount  of  heat  required  to  raise  a  kilogram  of 
water  from  o°  C  to  i°  C,  but  often  the  small  calorie  is  used — /.  <?.,  that 
required  to  raise  one  gram  of  water  from  o°  C  to  i°  C,  as  in  the 
centimeter-gram-second,  or  C.  G.  S.  system  of  physical  units  measure- 
ment. 

In  some  heating  and  ventilation  problems  it  is  convenient  to  ex- 
press the  amount  of  heat  in  terms  of  force,  and  vice  versa.  The  ther- 
mal unit  is  equivalent  to  772  foot-pounds  of  force.  The  calorie  is 
equal  to  423.985  kilogram-meters,  each  kilogram -meter  being  equal 
to  7.2  foot-pounds,  or  one  calorie  is  equal  to  3.956  -f-  thermal  units. 

We  have  chiefly  to  deal  with  the  questions  involving  the  amount 
of  heat  in  different  quantities  of  air,  and  of  water  and  watery-vapor, 
under  different  circumstances,  and  the  amount  produced  by  combus- 
tion of  given  quantities  of  fuel,  and  for  our  purposes  accurate  computa- 
tions are  unnecessary,  and  the  range  of  temperature  involved  is  com- 
paratively small.  The  specific  heat,  that  is,  the  amount  of  heat  re- 
. quired  to  heat  one  pound  i°  F.  is  for  water  one  thermal  unit,  increas- 
ing slightly  as  the  temperature  rises,  and  for  air  with  constant  press- 
ure, involving  increase  of  volume  by  expansion  with  rise  of  temperature, 
it  is  0.2379  thermal  unit.  If  the  volume  be  constant,  it  is  0.16866 
thermal  unit.  In  these  and  all  following  computations  it  is  assumed 
that  the  barometric  pressure  of  the  atmosphere  remains  constant  at 
the  standard  of  29.922  inches  of  mercury.  Under  these  circumstances 
one  pound  of  air  at  32°  F.  contains  12.387  cubic  feet,  or  i  cubic  foot 
of  air  weighs  0.080726  pound,  or  i  litre  of  air  =  0.035317  cubic  foot 
and  weighs  1.293187  grams,  the  gram  being  equal  to  0.00220462 
pound. 

As  air  under  constant  pressure  expands  as  the  temperature  rises,  a 
cubic  foot  of  air  weighs  less  when  its  heat  increases. 


210 


HEATING    OF    AIR. 


The  following  table  shows   the  weight  of  dry   air   at    different 
temperatures  : 

WEIGHT  OF  DRY  AIR  AT   DIFFERENT  TEMPERATURES,   THE   BAROMETER 
STANDING  AT  29.92   INCHES  OF   MERCURY. 


Cubic  Feet 
of  Air. 

WEIGHT  IN  POUNDS  AT  TEMPERATURE  F. 

32° 

3S 

40 

45 

50 

55 

60 

65 

70 

75 

80 

85 

90 

95 

100 

I05 

no 

100 

8.07 

8.02 

7-94 

7.86 

7-79 

7.*, 

7.64 

7-57 

7-50 

7-43 

7.36 

7.29 

7.23 

7.16 

7.10 

7.03 

6.97 

200 
300 

16.14 
24.21 

16.04 

2406 

15.88 
23  82 

I5-72 
23.58 

15-58 
23-37 

15-42 
23.13 

15.28 
22.92 

I5-I4 
22.71 

15.00 
22.50 

14.86 
22.29 

14.72 
22.08 

14.58 
21.87 

14.46 
21.69 

M-32 
21.48 

14.20 
21.30 

14.06 
21.09 

13-94 

20.91 

400 

32.28 

32.08 

3J-76 

3J-44 

31-16 

30.84 

30-56 

30.28 

30.00 

29.72 

29-44 

29.16 

28.92 

28.64 

28.40 

28.12 

27.88 

500 

4°-35 

40.10 

39-70 

39-3° 

38.95 

38.55 

38.20 

37.85 

37-50 

37-15 

36.80 

36.45 

36.15 

35-So 

35-50 

35-15 

34-85 

600 

48.42 

48.12 

47.64 

47.16 

46.74 

46.26 

45-84 

45.42 

45.00 

44-58 

44.16 

43-74 

43.38 

42.96 

42.60 

42.18 

41.82 

700 

56.49 

56.14 

55-58 

55-02 

54-53 

53-97 

S3-48 

52.99 

52.50 

52.01 

5I-52 

51-03 

50.61 

50.12 

49.70 

49.21 

48.79 

Soo 

64.56 

64.16 

63-52 

62.88 

62.32 

61.68 

61.12 

60.56 

60.00 

59-44 

58.88 

58.32 

57.84 

57.28 

56.80 

56.24 

55-76 

900 

72.63 

72.18 

71.46 

70.74 

70.11 

69-39 

68.76 

68.13 

67.50 

66.87 

66.24 

65-61 

65.07 

64-44 

63-90 

63.27 

62.73 

The  following  table  shows  the  amount  of  heat  required  to  raise 
the  temperature  of  a  given  weight  of  air  through  a  given  number  of 
degrees  Fahrenheit. 

NUMBER  OF  THERMAL  UNITS  REQUIRED  TO  HEAT  A  GIVEN  QUANTITY  OF  DRY 
AIR  A  CERTAIN  NUMBER  OF  DEGREES  FAHRENHEIT. 


HEATED. 


a 

J9 

o 

P-. 

I°33 

2°34 

3%5 

4%6 

5%, 

6%8 

7°39 

8°40 

9°4l 

100 

23-79 

47.58 

71-37 

95.16 

118.95 

142.74 

166.53 

190.32 

214.11 

200 

47-58 

95-16 

142.74 

190.32 

237.90 

285.481          333.06 

380.64 

428.22 

3OO 

7L37 

142.74 

214.11 

285.48 

356.85 

428.22 

499-59 

570.96 

642.33 

4OO 

95-16 

I9O.32 

285.48 

380.64 

475-80 

570.96      666.12 

761.28 

856.44 

500 

118.95 

237.90 

356.85 

475.8o 

594-75 

713.70 

832.65 

95  i  •  60 

1070.55 

600 

142  .  74 

285.48 

428.22 

570.96 

713.70 

856.44 

999.18 

1141  .92 

1284.66 

7OO 

166.53 

333-06 

499-59 

666.12 

832.65 

999.18 

1165.71 

1332.24 

1498.77 

800 

190.32 

380.64 

570.96 

761.28 

951.60 

1141.92 

1332.24 

1522.56 

1712.88 

900 

214.  ii 

428.22 

642.33 

856.44 

1070.54 

1284.66 

1498.77 

1712.88 

1926.99 

1 

HEATING    OF    AIR. 


211 


TABLE  SHOWING  THE  VOLUME  OF  DRY  AIR  AT  CERTAIN  DEGREES  OF  FAHRENHEIT, 
THE  VOLUME  AT  32  DEGREES  BEING  i.ooo. 


Temperature, 
Fahrenheit. 

Volume. 

Temperature, 
Fahrenheit. 

Volume. 

32° 

.OOO 

60° 

1.057 

35° 

.006 

65° 

1  .067 

40° 

.Ol6 

70° 

1.077 

45° 

.026 

75° 

1.087 

50° 

.036 

80° 

1.097 

55° 

1.046 

NUMBER  OF  THERMAL  UNITS  REQUIRED  TO  HEAT  A  GIVEN  QUANTITY  OF  DRY  AIR 
A  CERTAIN  NUMBER  OF  DEGREES  FAHRENHEIT,  COMMENCING  AT  32°  F. 


HEATED. 


Cubic  Feet. 

1° 

2° 

'3° 

4° 

5° 

6° 

7° 

8° 

9° 

IOO         

I  Q2 

a  8d 

5  76 

7  68 

960 

II  52 

1  1  44 

I  5  l6 

17  28 

2OO        .  . 

•7  84. 

7  68 

II  52 

jc  -26 

IQ  2O 

2"?  O4. 

26  88 

1O  72 

14  56 

1OO 

5  76 

I  J  52 

17  28 

2^  O4. 

28  80 

14  56 

4O  12 

46  08 

51  84 

4OO       ..... 

7  68 

15  l6 

2^  O4 

^O  72 

18  40 

46  08 

51  76 

6l  44 

6Q  12 

500  

Q  60 

19.20 

28  80 

38  40 

48  oo 

57  60 

67  2O 

76  80 

86  40 

600 

II  52 

23  oo 

riA  c6 

46  08 

C7  60 

69  12 

80  64 

02  1  6 

103  68 

7OO 

I  a  A  A 

26  88 

4O  12 

51   76 

67  2O 

80  64 

Q4  08 

IO7  52 

1  20  96 

800      

1C  ^6 

1O  72 

46  08 

6  1  44 

76  80 

Q2  l6 

IO7  52 

122  88 

1  18  24 

QOO       

17  28 

•34  56 

51  84 

69.  12 

86.40 

103  68 

1  2O  96 

Il8  24 

155  52 

NUMBER  OF  THERMAL  UNITS  REQUIRED  TO  HEAT  A  GIVEN  QUANTITY  OF  DRY  AIR 
A  CERTAIN  NUMBER  OF  DEGREES  CENTIGRADE  FROM  o°  C. 


HEATED. 


UUDIC  Meters. 

i° 

2° 

3°     i     4° 

5° 

6° 

7° 

8° 

9" 

i 

I 

1.22 

2.44 

3-66 

4.88 

6.10 

7.32 

8.54 

9.76 

10.9 

2 

2.44 

4.88 

7.32 

9.76 

12.20 

14.64 

17.08 

19.52 

21  .9 

3 

3-66 

7.32 

10.98 

14.64 

18.30 

21  .96 

25.62 

29.28 

32.9 

4                 '     4.88 

9.76 

14.64 

19.52 

24.40 

29.28 

34.16 

39.04 

43-9 

5                     6.10 

12.20 

18.30 

24.40 

30.50 

36.60 

42.70 

48.80 

54-9 

6 

7.32 

14.64 

21  .96 

29.28 

36.60 

43-92 

51-24 

58.56 

65.8 

7 

8.54 

17.08 

25.62 

34.i6 

42.70 

5L24 

59.78 

68.32 

76.8 

8 

9.76 

19.52 

29.28 

39-04 

48.80 

58.56 

68.32 

78.08 

87.8 

9 

10.98 

21.96 

32.94 

43-92 

54.90 

65.88 

76.86 

87.84 

98.8 

212  RADIATION    OF    HEAT. 

From  these  tables  it  is  easy  to  calculate  the  amount  of  heat  re- 
quired to  raise  the  temperature  of  any  given  quantity  of  air  through 
any  given  number  of  degrees  of  temperature.  Suppose,  for  example, 
that  we  wish  to  supply  to  a  hospital  ward  72,000  cubic  feet  of  air  per 
hour  and  that  we  are  to  provide  for  heating  it  from  32°  to  70°  or  38°  F. 
Then: 

70,000  cubic  feet  heated  30°  =  40,320  thermal  units. 
70,000  "         8°  =  10,752         "  " 

2,000  "  "       30°  =    1,152         "  " 

2,000  "  "         8°  =       307         "  " 


Total 52,531 

In  round  numbers  and  for  rough  calculations  we  may  assume  that 
one  thermal  unit  will  heat  50  cubic  feet  of  air  i°  F.  Applying  this 
rule  to  the  above  figures  we  have  72,000  -^  50  =  1,440  x  38  = 
54,720  thermal  units,  a  slight  excess  over  the  figures  derived  from  the 
table. 

Heat  is  usually  said  to  be  communicated  from  one  body  to  an- 
other by  three  processes — viz.,  radiation,  conduction  and  convection. 
Radiant  heat  passes  from  the  heated  body  in  straight  lines  in  every 
direction  until  it  is  intercepted  by  some  other  body.  It  diminishes  for 
a  given  area  as  the  square  of  the  distance  from  its  source,  and  it  does 
not  appreciably  heat  the  air  or  gases  through  which  it  passes.  For 
efficient  heating  by  pure  radiant  heat  the  temperature  of  the  heating 
body  must  be  comparatively  high,  at  least  that  of  a  dull  red  heat  of 
iron,  the  typical  form  of  this  kind  of  heating  being  by  the  glowing 
coals  in  an  open  grate  or  fireplace.  Conducted  heat  passes  from  one 
particle  of  matter  to  another  when  they  touch — /.  e.,  are  separated  by 
insensible  distances.  If  one  of  the  particles  of  matter  is  free  to  move, 
as. in  liquids  and  gases,  it  may  carry  the  heat  which  it  has  received  to 
another  point  and  there  part  with  it — this  being  what  is  called  con- 
vection, which  is  only  a  particular  form  of  conduction.  Heat  is  con- 
ducted readily  from  solids  to  liquids  or  gases,  and  from  these  to  solids, 
but  it  passes  only  to  a  very  limited  extent  from  one  particle  of  liquid 
or  gas  to  another  particle  of  liquid  or  gas. 

The  heating  of  a  room  is  technically  said  to  be  effected  by  direct 
radiation,  by  indirect  radiation,  by  direct-indirect  radiation,  or  by 
combinations  of  these  methods.  In  this  sense  direct  radiation  means 
that  the  heating  surfaces  are  placed  in  the  room  to  be  warmed,  and 
are  not  connected  with  the  air  supply,  so  that  the  incoming  air  is  not 
warmed.  Indirect  radiation  means  that  the  room  is  heated  by  air 
which  has  been  warmed  by  being  brought  into  contact  with  heated 


DIRECT    RADIATION.  213 

surfaces  placed  in  some  other  room,  usually  in  the  basement  or  cellar. 
Direct-indirect  radiation  means  that  the  heating  surfaces  are  placed 
in  the  room  to  be  warmed,  and  have  fresh  air  brought  in  around  or 
between  them,  so  that  it  is  warmed. 

Direct  radiation  includes  fireplaces,  ordinary  stoves,  and  pipes  or 
radiators  heated  by  steam  or  hot  water.  Of  these  the  fireplace  or 
open  grate  is  the  only  one  which  really  heats  entirely  by  radiation — 
the  greater  part  of  the  heat  furnished  by  stoves  and  radiators  being  con- 
vected — that  is,  conveyed  by  heating  the  air  which  flows  up  in  contact 
with  the  hot  surfaces.  It  also  includes  systems  for  heating  the  walls 
or  floor  of  the  room  by  various  means.  When  a  room  is  said  to  be 
heated  by  direct  radiation  it  may  in  most  cases  be  taken  for  granted 
that  it  has  no  special  provision  for  the  supply  of  fresh  air,  and,  there- 
fore, is  unventilated.  There  are,  however,  some  exceptions  to  this 
rule,  for  some  engineers  have  endeavored  to  use  direct  radiation,  and, 
at  the  same  time,  to  supply  fresh  air  which  is  not  to  be  warmed. 
Their  theory  is  that  it  is  healthier  and  more  pleasant  to  breathe  air  of  a 
temperature  of  from  35°  F.  to  55°  F.  than  to  breathe  air  at  a  tempera- 
ture of  65°  F.  or  70°  F.,  and  hence  that  a  proper  system  of  heating 
should  supply  by  radiation  from  fires,  walls,  etc.,  the  amount  of  heat 
requisite  for  comfort,  and,  at  the  same  time,  allow  the  air  to  remain 
comparatively  cool. 

This  is  the  teaching  of  Mr.  Leeds,1  and  also  that  of  M.  Emile 
Trelat,  who  argues  that  the  cooler  the  air  the  greater  its  density,  and, 
therefore,  the  more  oxygen  it  contains  in  a  given  bulk,2  and  the  more 
oxygen  the  better  for  respiratory  purposes. 

There  is,  however,  abundance  of  oxygen  in  ordinary  air  at  the 
temperature  of  70°  F.,  and  a  man's  sensations  while  walking  in  open 
air  of  this  temperature,  provided  it  does  not  contain  too  much  moisture, 
are  very  satisfactory.  The  lower  the  temperature  of  the  air  inhaled 
the  greater  (other  things  being  equal)  will  be  its  capacity  when  heated 
to  98°  F.  in  the  lungs  for  taking  up  moisture  from  the  lungs  and  air 
passages,  and  probably  the  greater  also  the  facility  with  which  certain 
volatile  organic  products  will  be  excreted  with  the  exhaled  breath,  but 
there  is  no  evidence  that  it  is  any  healthier  to  breathe  air  at  50°  F, 
than  at  70°  F.  provided  the  supply  of  fresh  air  is  abundant. 

Direct-radiation  systems  are  more  used  than  any  others  because 
they  are  cheaper  in  construction,  and  do  not  require  a  fresh-air  supply 

1  Leeds,  L.  W.     A  Treatise  on  Ventilation,  New  York,  1871. 

2  Theorie    du    Chauffage    des    Habitations,    Rev.    d'    hyg.    XIII. ,  1891, 
p.  1,087. 


214  FIREPLACES. 

to  enable  them  to  give  the  necessary  heat,  as  is  the  case  with  the 
indirect  system — hence  they  can  often  be  run  at  much  less  cost  for 
fuel.  This  is  not  the  case  with  the  open  fireplace,  which  is  the  most 
costly,  as  regards  fuel,  of  all  the  methods  of  warming — nevertheless, 
for  small  rooms  in  private  houses,  when  the  temperature  of  the  external 
air  is  not  below  32°  F.,  the  open  grate  will  be  preferred  by  many  to 
all  other  means  of  warming,  and  it  is  always  well  to  provide  for  it  in 
the  plans  of  such  buildings,  for  it  furnishes  a  good  outlet  flue  whether 
a  fire  be  used  in  it  or  not.  It  is  an  agreeable  addition  to  other  means 
of  heating,  but  it  is  dangerous,  difficult  to  regulate,  productive  of  dust 
and  noise,  and  requires  considerable  labor. 

In  very  cold  weather  the  fireplace  is  by  no  means  satisfactory  as  a 
source  of  heat,  and  in  our  Northern  cities  it  should  be  considered,  so 
far  as  heating  is  concerned,  as  merely  supplementary  to  the  furnace 
or  steam  heating,  or  even  to  the  common  air-tight  stove.  It  wastes 
from  75  to  90  per  cent,  of  the  fuel  consumed  in  it,  so  far  as  the  work  of 
warming  the  room  is  concerned.  Although  this  great  waste  of  heat 
from  the  ordinary  fireplace  is  universally  admitted,  there  have  been 
but  few  careful  observations  made  on  the  subject.  Among  these  are 
those  reported  by  Mr.  J.  P.  Putnam,  in  his  very  interesting  book,  "  The 
Open  Fireplace  in  all  Ages."  Boston,  1881. 

Although,  as  its  title  indicates,  this  work  is  largely  historical,  yet 
it  is  much  more  than  this,  for  the  author  has  not  been  satisfied  to  be 
merely  a  collector  and  critic  of  the  work  of  others,  but  has  undertaken 
to  investigate  for  himself  the  action  of  fireplaces  and  heaters  of  various 
kinds,  and  gives  as  the  result  some  valuable  original  data,  to  which,  it 
is  to  be  hoped,  that  architects,  furnace  manufacturers  and  heating 
engineers  will  give  special  attention.  The  first  series  of  experiments 
detailed  by  Mr.  Putnam  simply  confirm  the  statements  of  Morin  and 
Peclet  as  to  the  enormous  loss  of  heat,  and  the  consequent  waste  of 
fuel  consumed  in  producing  it,  in  the  use  of  an  ordinary  fireplace. 
He  found  that  in  using  dry  pine  wood  only  about  6  per  cent,  of  the 
heat  generated  by  the  fuel  was  utilized  in  warming  the  room.  In  a 
room  29'x2o'xio',  six  and  a  half  pounds  of  dry  wood  raised  the  average 
temperature  of  the  room  only  a  little  over  i°  F.,  although  the  heat 
generated  was  sufficient  to  raise  the  temperature  of  14  rooms  of  equal 
size  from  freezing  to  68°  F. 

Another  series  of  experiments  was  made  with  ventilating  fireplaces 
of  two  different  patterns  set  in  the  same  room  in  which  the  trials  of  the 
common  fireplace  were  made.  In  the  first  of  these,  made  with  what  is 
called  the  fireplace  heater,  about  13  per  cent,  of  the  heat  from  the 


FURNACES.  215 

burning  wood  was  utilized,  or  about  twice  as  much  as  in  the  ordinary 
fireplace.  The  second  form  of  apparatus  tried  was  the  Dimmick 
heater,  and  Mr.  Putnam  calculates  that  with  this  18  per  cent,  of  the 
heat  produced  was  utilized. 

The  point  to  which  attention  is  called  is  not  the  relative  value  of 
this  or  that  form  of  apparatus,  for,  as  a  matter  of  fact,  the  data  given 
are  not  sufficient  to  determine  the  point  with  precision  ;  but  it  is,  that 
we  have  in  this  work  an  attempt  to  employ  the  experimental  method 
in  a  scientific  manner,  in  order  to  settle  the  question  of  such  relative 
values,  and  that  this  is  the  only  possible  method  by  which  we  can  ob- 
tain positive  scientific  data  on  the  subject.  It  is  not  sufficient  to  try 
experiments.  Every  proprietor  of  a  furnace  or  heater,  of  any  kind, 
has  done  that,  and  is  prepared  to  say  that  he  has  satisfied  himself  by 
experiment  of  the  value  of  his  apparatus.  To  be  of  value  the  experi- 
ments must  be  made  and  the  results  must  be  recorded  in  a  scientific 
manner.  Mr.  Putnam  has  endeavored  to  do  this  by  testing  the  different 
forms  of  apparatus,  as  far  as  possible,  under  the  same  circumstances, 
placing  them  successively  in  the  same  room,  using  the  same  kind  of 
fuel  and  for  the  same  length  of  time,  and  then  recording  the  results  by 
instruments  of  precision — by  the  thermometer  and  the  anemometer — 
instead  of  giving  vague  and  useless  opinions  as  to  whether  one  was 
better  than  another. 

It  is  true,  as  mentioned  above,  that  the  data  are  not  as  complete 
as  could  be  wished;  for  example,  we  are  not  told  in  each  case  how 
many  cubic  feet  of  air  escaped  at  the  top  of  the  chimney,  and  at  what 
temperature,  during  the  time  of  each  experiment.  This  must  be  ob- 
served, and  not  merely  calculated  or  inferred,  in  order  to  determine 
the  number  of  heat  units  thus  escaping,  but  if  we  could  only  obtain, 
from  reliable  authority,  data  for  every  form  of  heating  apparatus  sim- 
ilar to  those  given  in  this  work,  it  would  be  a  long  stride  toward  placing 
the  subject  of  heating  and  ventilation  on  a  sound  basis. 

As  this  book  is  thus  recommended,  it  seems  desirable  to  point  out 
what  seems  to  be  a  fallacious  line  of  reasoning  in  its  first  chapter — a 
fallacy  which,  while  not  materially  detracting  from  the  interest  and 
value  of  the  work,  should  nevertheless  be  understood  by  its  readers. 
The  first  chapter  begins  as  follows: 

"  That  great  radiator  of  heat  to  all  living  beings,  the  sun,  furnishes 
those  beings  with  the  kind  of  heat  best  suited  to  support  the  life  which 
it  has  developed,  namely,  that  of  direct  radiation.  If  we  would  only 
accept  this  lesson,  repeated  every  day  as  if  for  the  purpose  of  giving  it 
all  possible  emphasis,  in  a  manner  the  most  impressive,  and  with  appa- 


1 


2l6  FURNACES. 

ratus  the  most  magnificent  that  Nature  can  furnish  or  the  mind  of  man 
imagine;  if  we  would  accept  the  lesson  and  endeavorto  heat  our  houses 
after  the  same  principles,  these  houses  might  be  made  as  healthy  as  the 
open  fields. 

"  We  should  be  prompted  to  respect  more  the  open  fireplaces  as 
furnishing  the  best  substitute  for  the  life  and  health-giving  rays  of  the 
sun,  and  to  discard  all  such  systems  of  heating  as  are  opposed  in  prin- 
ciple to  that  employed  by  Nature." 

Precisely  this  form  of  argument  is  used  to  advocate  vegetarianism, 
long  hair,  going  naked,  communism,  and  every  other  sort  of  "  ism  "  and 
"  pathy  "  which  its  advocates  choose  to  consider  in  accord  with  what 
they  are  pleased  to  call  "nature."  The  notion  that  in  order  to  make 
our  houses  as  healthy  as  the  open  fields,  all  that  is  necessary  is  to  heat 
them  by  direct  radiation,  will  simply  bring  a  smile  to  the  face  of  every 
educated  physician  or  sanitarian.  The  author  himself  forgets  his  com- 
mencing axiom  very  soon,  for  on  page  10  we  find  him  stating  that  ideal 
perfection  would  imply  that  the  supply  of  fresh  air  introduced  into  the 
house  shall  be  warmed  in  winter  to  a  temperature  somewhat  below  that 
of  the  room,  and  all  of  his  suggestions  in  the  latter  part  of  the  book 
for  so  arranging  the  flues  of  open  fires  as  to  warm  the  fresh-air  supply 
of  the  room  relate  to  increasing  the  supply  of  heat  by  indirect  and  not 
by  direct  radiation. 

It  is,  in  fact,  in  this  direction  only  that  practical  improvement  in 
the  economics  of  heating  is  to  be  hoped  for,  since  it  is  not  possible  to 
increase  the  amount  of  heat  to  be  obtained  by  direct  radiation  from 
a  given  amount  of  fuel,  and  at  the  same  time  secure  a  sufficient 
ventilation,  beyond  what  the  fireplaces  of  Gauger  and  Rumford 
will  effect.  To  secure  the  best  effects  from  direct  radiation  a 
high  temperature  with  a  correspondingly  rapid  consumption  of  fuel  is 
necessary. 

To  say  that  the  heating  of  rooms  by  close  stoves,  or  by  steam  or 
hot-water  radiators  placed  in  the  room  to  be  warmed,  is  heating 
by  direct  radiation,  is  the  phrase  in  common  use  ;  the  greater  part 
of  the  effect  of  such  appliances  is  due  not  to  radiant,  but  to  convected 
heat— to  the  circulation  of  air  heated  by  coming  in  contact  with 
them. 

All  this  is  understood  by  Mr.  Putnam,  who  says  that  the  system 
of  tubes  which  he  proposes  to  arrange  above  the  fireplace  to  heat  the 
fresh  air  should  properly  be  called  a  convector. 

We  close  these  remarks  by  quoting  a  passage  from  the  book,  which 
carries  its  own  moral.  The  picture  of  the  proprietors  and  workmen 


VENTILATING    FIREPLACES.  2iy 

standing  around  and  staring  with  astonishment  at  the  results  of  the 
test  ought  to  have  been  given  by  the  pencil  as  well  as  by  the  pen  : 

"  Furnace  makers  will  claim  that  the  peculiar  kind  of  cement 
they  use,  or  their  peculiar  method  of  hammering  the  joints,  will  pre- 
vent leakage  and  stand  fire.  The  writer  visited  a  furnace  advertised 
by  the  makers  to  be  absolutely  gas-tight.  The  joints  were  numerous. 
In  some  joints  cast  iron  was  connected  with  wrought.  Pipes  of  cast 
iron  were  set  into  wrought-iron  plates — an  arrangement  the  reverse  of 
that  used  in  the  Dunklee  furnace.  To  this  the  writer  particularly 
objected,  and  inquired  of  the  makers  if  they  could  warrant  the  furnace 
to  stand  tests  at  these  points.  The  method  of  making  these  joints 
was,  they  cl aimed, peculiar. 

"  No  cement  was  used,  and  so  great  was  the  care  bestowed  on 
each  joint  that  leakage  was  a  sheer  impossibility.  A  fine,  new  furnace 
was  exhibited  to  show  the  excellence  of  the  workmanship.  The 
writer  still  objected,  until  challenged  by  the  makers  to  give  proof  of 
any  of  the  numerous  furnaces  put  up  by  the  company  having  ever 
leaked  gas.  Without  taking  the  time  to  visit  any  or  all  of  the  500  or 
more  gentlemen  whose  letters  of  recommendation  adorned  the  descrip- 
tive circular  of  the  firm,  the  writer  expressed  himself  satisfied  if  the 
fine,  new  sample  furnace  then  on  exhibition  would  itself  stand  the  test. 
With  the  assurance  that  he  was  at  liberty  to  make  any  reasonable  test  he 
pleased,  he  ordered  the  furnace  to  be  turned  over  and  water  poured 
into  all  the  joints.  To  the  complete  astonishment  of  the  proprietors 
and  of  the  careful  workmen  standing  around,  the  water  which  was 
poured  in  poured  out  again  through  nearly  every  one  of  the  score  of 
careful  joints,  until  the  furnace  seemed  to  dissolve  and  float  away  in 
its  own  tears."  (Pp.  119-20.) 

The  majority  of  those  who  write  on  the  beauties  of  warming  by 
open  fireplaces  in  this  country  have  had  no  experience  of  fireplace 
warming  with  the  external  temperature  at  10°  F.,  or  lower. 

Some  trials  were  made  several  years  ago,  in  our  small  army  hospi- 
tals, of  double  fireplaces,  placed  back  to  back,  and  so  arranged  that  the 
fresh  air  was  introduced  between  them,  and  warmed  before  it  escaped 
into  the  room.  With  anthracite  coal  these  double-ventilating  fire- 
places worked  very  well  when  the  external  temperature  was  above  30° 
F.,  giving  excellent  ventilation  and  very  fair  heating  ;  but  when  the 
external  temperature  was  near  zero,  and  when  only  wood  or  soft  coal 
was  available,  it  seemed  as  if  the  more  fire  was  made  the  colder  it  got, 
since  the  incoming  air  was  not  sufficiently  warmed,  and  at  times  it  ap- 
peared as  if  the  inmates  might  be  frozen  to  death  by  their  own  fire- 


2l8  FURNACES. 

places.  The  great  majority  of  the  small  dwelling  houses,  or  living 
rooms,  in  this  country,  are  heated  by  stoves,  because  this  is  the 
cheapest  method.  Architects  and  engineers  seldom  or  never  have 
anything  to  do  with  the  plans  or  specifications  for  buildings  of  this  kind, 
since  their  builders  are  usually  their  own  architects. 

There  are  a  number  of  patent  stoves,  which  act  upon  the  principle 
of  the  ventilating  fireplace,  but  the  amount  of  air  introduced  and 
warmed  by  them  is  usually  small.  For  small  rooms,  occupied  by  only 
one  or  two  persons,  they  answer  very  well,  but  in  a  large  room,  con- 
taining many  persons,  it  is  extremely  difficult,  if  not  impossible,  to 
secure  a  satisfactory  introduction  and  distribution  of  fresh  air  by  any 
form  of  stove  placed  in  the  room  itself.  The  stove  must  be  placed 
below  the  room  to  be  warmed  ;  in  other  words,  it  must  be  converted 
into  a  furnace.  The  great  majority  of  hot-air  furnaces  as  actually 
used  are  unsatisfactory,  and  special  sources  of  danger  to  health,  but 
this  is  not  so  much  the  fault  of  the  furnaces  themselves  as  of  the 
manner  in  which  they  are  set  and  adjusted.  They  are  better  than 
stoves  in  this  respect,  that  satisfactory  heating  cannot  be  secured  by 
them  without  the  introduction  of  air  into  the  room  to  be  heated,  but 
the  air  that  is  introduced  by  them  is  often  of  a  very  unsatisfactory 
quality. 

If  a  building  is  to  be  heated  by  a  hot-air  furnace,  the  following 
points  should  be  borne  in  mind  in  its  selection  and  adjustment  : 

First. — In  99  out  of  every  100  buildings  in  this  country  in  which 
this  method  of  heating  is  used,  the  furnace  is  too  small.  The  result 
of  this  is,  that  in  cold  weather,  in  order  to  secure  comfort,  it  is  neces- 
sary to  raise  the  heating  surface  to  a  high  temperature,  often  to  a  red 
heat.  The  contraction  and  expansion  due  to  such  great  changes  of 
temperature  soon  loosen  the  joints  of  furnaces  built  up  of  several  pieces, 
and  permit  the  escape  of  the  gases  of  combustion  into  the  fresh-air 
supply.  Of  these  gases,  carbonic  oxide  and  sulphurous  acid  are  the 
most  hurtful. 

The  sulphur  compounds,  when  present  in  harmful  quantity,  are  so 
perceptible  to  the  smell  and  create  irritation  of  the  air  passages  to  such 
an  extent  as  to  soon  call  attention  to  the  evil  and  lead  to  attempts  to 
remedy  it.  Carbonic  oxide  is  odorless.  When  present  in  small  quanti- 
ties, it  produces  a  peculiar  feeling  of  discomfort,  somewhat  as  if  a 
tightly-fitting  band  were  drawn  around  the  head,  increasing  to  a  dull, 
persistent  headache,  with  slight  giddiness,  languor  and  disinclination 
for  either  mental  or  physical  exertion.  This  gas  will  pass  through 
red-hot  cast  iron,  and  this  fact  is  much  insisted  on  by  the  manufactur- 


FURNACES.  219 

ers  of  wrought-iron,  soapstone  or  brick  furnaces.  The  special  danger 
on  this  account  from  a  cast-iron  furnace  is  probably  extremely  small; 
it  is  much  more  due  to  defective  castings  containing  sand  holes,  or  to 
badly-fitting  joints. 

As  Mr.  E.  S.  Philbrick  has  pointed  out,*  wrought-iron  furnaces 
are  by  no  means  faultless  as  regards  leakage,  "  for  if  often  heated  to 
redness  they  suffer  such  strains  by  the  expansion  and  contraction 
which  always  accompanies  heating  and  cooling,  that  the  joints  will  be 
apt  to  fail,  or  other  cracks  open  in  a  little  time."  Moreover,  wrought 
iron  oxidizes  much  more  rapidly  than  cast  iron,  and  will  fail  sooner 
from  this  cause.  It  may  be  safer  when  new,  but  is  more  perishable. 
Brick,  clay  or  tile  furnaces  are  not  much  used  in  this  country.  They 
take  up  much  more  room  than  iron  furnaces,  but  have  the  advantage 
of  giving  a  much  larger  heating  surface  at  a  comparatively  low  temper- 
ature. 

Second. — As  furnaces  are  usually  set,  there  is  no  provision  for  mix- 
ing cool  air  with  the  heated  air.  The  result  of  this  is,  that  the  air  is 
delivered  in  the  room  at  a  high  temperature — often  at  140°  F.,  and 
sometimes  higher — and  the  only  way  to  prevent  the  room  from  be- 
coming too  warm  is  to  close  the  register,  which,  of  course,  shuts  off 
the  supply  of  fresh  air. 

Third. — The  source  of  air  supply  to  a  furnace  is  often  very  unsatis- 
factory. Sometimes  it  is  taken  directly  from  the  cellar  itself,  in  which 
case  it  is  almost  sure  to  be  contaminated  with  gases  escaping  from  the 
furnace  door,  while  the  cellar  itself  contains  decaying  vegetables,  slop 
buckets,  and  perhaps  an  empty  bell  trap,  giving  free  communication 
with  the  sewer;  or  the  air  box  from  the  outer  air  to  the  furnace  passing 
through  the  cellar  may  have  so  many  cracks  and  loose  joints  that  the 
cellar  air  finds  an  easy  entrance  to  it.  The  fresh-air  supply  should  not 
be  brought  in  through  an  underground  duct  without  taking  special 
precautions  to  have  it  air-tight,  and  it  should  not  pass  across  or  near 
a  drain  or  sewer. 

As  a  rule,  architects  make  no  special  provision  for  the  fresh-air 
supply  to  a  furnace,  and  the  furnace  setter  is  left  to  adjust  this  as  best 
he  can,  the  result  being  that  he  will  often  select  that  method  which 
involves  the  least  trouble  and  expense,  but  which  also  will  give  the 
least  satisfactory  result. 

Fourth. — A  furnace  is  usually  placed  near  the  center  of  a  build- 
ing, the  object  being  to  have  the  flues  conveying  the  heated  air  from  it 

*  See  Material  for  Stoves,  The  Sanitary  Engineer,  Vol.  III.,  page  3. 


220  STEAM    HEATING. 

as  short  and  with  as  rapid  an  ascent  as  possible.  Horizontal  flues  for 
heated  air  are  very  undesirable,  as  the  friction  in  them  checks  the  cur- 
rent and  involves  loss  of  heat.  The  direction  of  the  wind  has  a  great 
influence  on  the  action  of  hot-air  flues,  and  for  this  reason  it  is  better 
to  place  the  furnace  not  in  the  center,  but  toward  that  side  of  the 
house  against  which  the  winter  winds  blow  most  frequently  and 
strongest.  In  this  vicinity  this  will  be  toward  the  northwest.  If  a 
building  of  large  area  is  to  be  warmed  by  furnace  heat,  it  will  be  much 
better  to  use  two  or  three  furnaces  distributed  over  the  area  than  one 
large  central  one. 

It  is  not  proposed  to  discuss  the  merits  of  the  various  patterns  of 
furnaces  now  in  the  market,  but  it  may  be  said  in  regard  to  them 
that- those  which  have  the  fewest  joints  and  the  largest  amount  of 
radiating  surface  in  proportion  to  the  size  of  the  fire  box,  are  to  be 
preferred — other  things  being  equal — and  that  it  is  very  poor  economy 
to  buy  a  furnace  which  is  not  large  enough  to  furnish,  in  the  coldest 
weather,  all  the  heat  required,  without  bringing  the  fire  pot  to  a  red 
heat. 

In  this  country  nearly  all  large  public  buildings  are  heated  by 
steam,  and  in  preparing  plans  for  such  edifices  our  architects  take  it 
for  granted  that  this  method  will  be  employed,  unless  specific  direc- 
tions to  the  contrary  are  given  by  the  building  authorities. 

The  cases  in  which  hot-water  apparatus  is  used  in  such  buildings 
are  comparatively  few,  this  form  of  heating  in  this  country  being  for 
the  most  part  confined  to  dwelling  houses,  hospitals  and  greenhouses. 

The  reasons  why  steam  has  thus  obtained  the  preference  over  hot 
water  are  worth  considering.  As  a  rule,  our  architects  give  little  atten- 
tion to  the  details  of  heating  apparatus,  and  prepare  their  plans  with- 
out any  special  reference  to  such  details,  other  than  providing  space 
and  a  chimney  flue  for  the  boiler,  and  other  flues  in  the  walls. 

They  rely  for  all  details  upon  those  firms  who  supply  heating 
apparatus,  and  are  guided  by  their  advice  to  a  great  extent  in  the 
selection. 

The  firms  which  make  a  business  of  furnishing  steam  and  hot- 
water  apparatus  are  comparatively  few,  for  the  business  is  one  which 
requires  large  capital;  but,  few  as  they  are,  not  all  of  them  employ  a 
properly-educated  engineer  to  prepare  their  plans  and  specifications, 
or  to  supervise  the  setting  of  their  apparatus. 

Now,  it  is  very  much  easier  to  plan  and  set  up  a  steam-heating 
apparatus  which  will  work,  than  to  do  the  same  with  a  hot-water  ap- 
paratus. Please  observe  that  the  statement  is  "  which  will  work," 


STEAM    HEATING.  221 

and  not  "  which  will  work  properly,  and  be  also  the  most  economical 
as  to  construction  and  maintenance;"  and  there  are  also  omitted  in  this 
connection  all  considerations  as  to  the  securing  of  proper  ventilation. 

In  a  steam  apparatus  it  is  not  necessary  that  the  boiler  shall  be 
on  a  lower  level  than  the  heating  surfaces,  and  much  greater  inequali- 
ties and  more  frequent  alterations  in  the  levels  .of  the  flow  and  return 
pipes  are  permissible  than  is  the  case  with  hot  water.  In  a  hot-water 
apparatus  a  mistake  of  a  few  inches  in  the  height  of  a  pipe  may  pre- 
vent the  working  of  the  whole  system.  In  a  steam  apparatus  the 
injurious  effects  of  miscalculation  as  to  areas  of  pipes  or  of  radiating 
surface  may,  to  a  considerable  extent,  be  overcome  by  increasing  the 
pressure  in  the  boiler,  although  at  an  undue  expense  for  fuel,  while 
this  can  only  be  done  within  very  narrow  limits  in  a  hot-water  appa- 
ratus. 

As  the  radiating  surfaces  in  steam  heating  are  kept  at  a  higher 
temperature  than  when  hot  water  is  used,  the  radiators  may  be  made 
smaller  and  more  compact',  and  thus  be  more  convenient  in  some 
places  than  the  larger  hot-water  coils.  It  is  also  easier  to  "scamp" 
a  steam-heating  job  than  a  hot-water  one. 

The  very  general  use  of  steam  as  a  source  of  power  has  made  a 
large  number  of  workmen  familiar  with  the  boilers  and  fittings  re- 
quired for  its  use,  and  these  can  be  everywhere  obtained  without  dif- 
ficulty. 

For  all  these  reasons,  in  addition  to  the  important  one  that  the 
plant  for  a  steam-heating  apparatus  is  cheaper  than  for  a  hot-water 
one,  it  has  come  to  pass  that  there  are  but  a  few  firms  in  this  country 
which  recommend  hot-water  apparatus  under  any  circumstances,  or 
which  are  willing  to  undertake  repairs  or  alterations  in  such  apparatus. 
Hood  states  that  "  the  first  cost  incurred  for  the  erection  of  the  two 
kinds  of  apparatus  will  differ  but  little  when  the  work  is  done  in  an 
equally  substantial  manner;  but  the  wear  and  tear  and  repairs  of  a 
hot-water  apparatus  will  be  less  than  that  of  a  steam  apparatus,  as  in 
the  former  there  is  absolutely  nothing  that  can  wear  out  except  the 
boiler,  while  in  a  steam  apparatus  there  are  various  things  which  con- 
stantly require  attention  and  repair  in  addition  to  the  greater  amount 
of  wear  in  the  steam  boiler  itself,  caused  by  the  large  quantities  of 
sediment  which  requires  to  be  constantly  removed." 

The  principal  disadvantages  of  a  steam-heating  apparatus  are  as 
follows  : 

First. — It  requires  constant  attention  to  keep  up  the  supply  of 
heat,  for  as  soon  as  the  production  of  steam  in  the  boiler  ceases  the 


222  STEAM    HEATING. 

radiating  surfaces  cool  rapidly.  This  is  claimed  as  an  advantage  in  the 
steam-heating  apparatus  for  rooms  that  are  to  be  occupied  but  a  few 
hours  each  day,  on  the  ground  that  it  furnishes  the  heat  only  when  it 
is  actually  wanted,  and  is,  therefore,  more  economical  than  a  hot-water 
apparatus  from  which  heat  continues  to  radiate  for  several  hours  after 
the  necessity  for  it  has  ceased.  While  this  is  true  to  a  certain  extent, 
it  should  be  remembered  that  to  secure  comfort  in  cold  weather  the 
walls,  floors,  etc.,  of  a  room  must  be  warmed  to  a  certain  point,  and 
that  heat  must  be  expended  in  doing  this  whenever  these  surfaces  are 
allowed  to  cool,  so  that  the  shutting  off  the  supply  of  heat  is  by  no 
means  a  clear  gain. 

Second. — Owing  to  the  high  temperature  of  steam  radiators  as 
compared  with  hot-water  ones,  it  is  more  difficult  with  the  former  to 
regulate  the  supply  of  heat  in  accordance  with  the  demands  of  our 
very  variable  climate  without  interfering  with  the  amount  of  air  sup- 
ply. As  steam-heating  apparatus  is  usually  arranged,  the  only  way  to 
diminish  the  heat  is  to  either  close  the  register,  which  cuts  off  the 
supply  of  fresh  air,  or  to  turn  off  the  steam  from  the  radiator,  which 
will  give  an  insufficient  supply  of  heat.  The  result  is  that  the  great 
majority  of  steam-heated  rooms  are,  during  many  days  in  the  year,  too 
hot,  and  at  the  same  time  have  an  insufficient  supply  of  fresh  air,  pro- 
ducing much  the  same  kind  of  discomfort  as  an  ordinary  hot-air  fur- 
nace, although  in  a  somewhat  less  degree.  This  evil  can  be  remedied  in 
several  ways.  The  first  is  to  arrange  each  set  of  radiators  in  several 
distinct  sections,  in  each  of  which  the  flow  of  steam  can  be  controlled 
independent  of  the  others,  so  that  when  but  little  heat  is  required  only 
one  section  need  be  used,  and  so  on  in  proportion  to  the  external 
temperature. 

Such  a  radiator,  as  arranged  by  Baker,  Smith  &  Co.,  of  New 
York,  is  shown  in  Fig.  23. 

The  radiator  is  divided  in  the  base  by  partitions  //,  so  as  to 
separate  each  row  of  tubes  into  a  different  radiator,  as  it  were  ;  each 
radiator  or  section  having  its  own  set  of  valves — /.  e.f  steam,  return  and 
air  valve.  The  pipe  d  is  the  steam  supply  to  a  header  a,  into  which  are 
nipped  as  many  valves  c,  as  there  are  sections  in  the  radiator  These 
valves  in  turn  are  connected  with  the  base  of  the  radiator  by  right  and 
left-handed  nipples  b.  In  like  manner  the  return  valve  c'y  header  a',  and 
return  pipe  ^/complete  the  return  end  of  the  radiator.  These  heaters 
are  made  as  wide  as  six  sections,  and  have  small  holes  <?,  through  the 
base,  to  allow  a  somewhat  better  contact  of  the  air  within  the  pipes 
than  could  be  had  with  wide  bases  if  they  were  not  perforated. 


STEAM    HEATING. 


22.3 


Practically,  such  direct  radiators  managed  by  inexpert  hands  are 
apt  to  give  trouble  by  noise  or  by  freezing  of  condensed  water  in  some 
of  the  pipes.  Where  the  heaters  are  connected  with  a  blower  system 
under  the  management  of  an  engineer,  this  method  of  shutting  off  a 
part  of  the  system  may  work  very  well. 

It  is  also  possible  in  many  cases  to  so  arrange  the  apparatus  that 
instead  of  the  usual  valves  on  the  inlet  and  outlet  pipes  to  each  radi- 
ator, both  of  which  must  be  entirely  closed  or  wide  open,  a  single 


ELEVATION  . 


o  o  o o  o  o  op 

-•- ®— -/°-  —  O—  O  -O—  O— O 

oooooooo 

—  O <g>- -O- -O— x2- -O- -O- - 

OOOOOOOO 


PLAN 
FIG.  23. 


valve,  such  as  the  one  invented  by  Mr.  Tudor,  and  described  on 
page  616,  Vol.  VIII.,  of  The  Sanitary  Engineer,  placed  on  the  inlet  will 
control  the  steam  supply  without  risk  of  condensed  water  being  driven 
back  into  the  radiator. 

A  second  mode  of  remedying  the  evil  is  to  so  arrange  the  air 
ducts  and  flues  that  by  the  movement  of  a  valve  the  air  can  be  at 
pleasure  made  to  pass  either  wholly  in  contact  with  the  radiating  sur- 


224  STEAM    HEATING. 

faces  or  wholly  separate  from  them,  or  partly  in  one  way  and  partly  in 
the  other,  in  such  proportions  as  may  be  desired.  Various  forms  of 
by-passes  for  this  purpose  are  described  in  the  following  chapter. 
By  this  method  very  excellent  results  may  be  secured,  but  it  requires 
careful  adjustment  of  the  valves  and  flues  and  constant  supervision. 

Third. — The  noises  produced  in  a  steam-heating  apparatus,  due 
to  the  presence  of  steam  and  water  in  the  same  pipe,  but  flowing  in 
opposite  directions,  and  technically  known  as  "  water  hammer,"  are 
often  very  disagreeably  prominent,  especially  where  a  series  of  radia- 
tors in  a  horizontal  line  discharge  their  condensed  water  into  one 
return.  Water  hammer,  however,  can  be  avoided  if  the  apparatus  is 
properly  constructed,  and  in  such  a  case  as  that  just  supposed  it  will 
be  prevented  by  keeping  the  return  on  a  level  below  the  water  line  in 
the  boiler. 

Fourth. — A  steam-heating  apparatus  is  somewhat  more  dangerous 
than  a  hot-water  one,  but  if  it  is  set  and  managed  with  good  ordinary 
intelligence  the  danger  is  very  slight.  The  automatic  adjustments  are 
now  so  satisfactory  in  steam  boilers  for  this  class  of  work  that  an  ex- 
plosion is  hardly  possible,  and  the  danger  of  fire  from  steam  pipes  is 
very  small.  Such  danger,  however,  exists,  and  it  should  be  remem- 
bered in  carrying  steam  pipes  on  or  near  wooden  surfaces. 

It  is  not  my  purpose  to  give  details  of  forms  of  apparatus,  methods 
of  construction,  etc.,  such  as  should  be  indicated  in  the  plans  and 
specifications  for  the  steam  or  hot-water  heating  of  a  particular 
building.  What  I  do  aim  at  is  to  give  to  the  architect  or  builder  the 
information  which  will  enable  him  to  fix  the  size  and  location  of  the 
radiators  needed,  the  size  and  location  of  the  mains  and  accelerating 
coils,  the  size  and  location  of  the  boiler,  and  the  size  and  location  of 
the  chimney  for  the  boiler.  He  can  then  furnish  these  data  to  the 
heating  engineers  or  firms  whom  he  prefers  and  ask  them  to  state 
their  price  for  the  work,  and  give  details  as  to  the  particular  kind  of 
boiler,  valves,  radiators,  etc.,  which  they  propose  to  use. 

A  general  specification  to  the  effect  that  the  building  must  be 
warmed  to  70°  F.  when  the  external  air  is  at  zero,  or  even  that  it  must 
be  so  warmed  with  a  certain  specified  amount  of  change  of  air  for  each 
room  is  practically  worthless  if  the  work  is  to  be  let  by  contract  to  the 
lowest  bidder. 

It  is  possible  to  construct  a  heating  apparatus  which  will  meet 
such  requirements  for  a  year  or  so — just  long  enough  to  enable  the 
contractor  to  obtain  his  final  payments,  and  which  will  soon  after 
break  down  utterly — and  to  furnish  such  an  apparatus  for  a 


RADIATING    SURFACE.  225 

price  20  or  30  per  cent,  lower  than  that  which  would  be  demanded  for 
one  which  will  do  its  work  for  from  10  to  20  years  with  only  trifling 
repairs.  The  broad  outlines  of  the  system  of  heating  and  ventilation 
to  be  used  should  be  decided  on  in  the  sketch  plans,  and  all  smoke 
and  air  flues,  radiators,  accelerating  coils  and  mains  should  be  ac- 
curately located,  and  their  sizes  defined  on  the  first  set  of  working 
drawings. 

Taking  the  approximate  estimate  given  above,  that  one  thermal 
unit  will  heat  50  cubic  feet  of  air  i  degree,  which  is  from  2  to  5  feet 
less  than  the  actual  quantity  and  is  therefore  a  safe  estimate,  we  have 
next  to  consider  the  amount  of  heat  that  is  given  off  from  heating 
apparatus. 

The  amount  of  heat  given  off  from  wrought  or  cast-iron  pipes  heated 
by  steam  or  hot  water  varies  from  1.15  to  2.25  thermal  units  per  hour 
per  square  foot  of  radiating  surface  for  each  degree  Fahrenheit  of  differ- 
ence between  the  temperature  of  the  pipe  and  that  of  the  surrounding 
air,  the  difference  depending  upon  the  shape  and  relations  of  the  sur- 
faces to  each  other  and  the  relative  amounts  of  heat  removed  by  direct 
radiation  or  by  convection.  For  a  direct  radiator  with  vertical  tubes 
it  may  be  taken  as  1.75  thermal  units — for  an  indirect  radiator  as 
1.15  thermal  units,  per  square  foot  per  hour  for  each  degree  of  differ- 
ence in  temperature.  Hence,  to  find  the  number  of  square  feet  of 
radiating  surface  required  to  heat  a  given  supply  of  air  to  a  given  tem- 
perature, multiply  the  number  of  cubic  feet  of  air  per  hour  by  the  differ- 
ence between  the  temperature  of  cold-air  supply  and  that  to  which  it  is  to 
be  heated  and  divide  it  by  50,  which  will  give  the  number  of  thermal 
units  required,  and  by  dividing  the  number  of  thermal  units  by  the  differ- 
ence between  the  temperature  of  the  radiator  and  that  of  the  surrounding 
air  multiplied  by  1.75  for  direct  and  by  1.15  for  indirect  radiators,  the 
number  of  square  feet  of  surface  required  will  be  found.  For  example, 
if  a  room  is  to  have  6,000  cubic  feet  of  air  supply  per  hour,  to  be  heated 
from  zero  to  70°  F.  by  a  direct-steam  radiator  whose  temperature  is 

210°  F.,  then  -?—       -~?-  =  8,400  thermal  units,  and  -  —=34.3 

square  feet  of  radiating  surface  are  required  to  do  this  work.  In  addi- 
tion to  this,  the  loss  of  heat  from  windows  and  walls  must  be  provided 
for,  as  will  be  explained  hereafter. 

Tredgold's  rule  is,  mutiply  the  number  of  cubic  feet  of  air  to  be 
heated  per  minute  by  the  difference  between  the  temperature  at  which 
the  room  is  to  be  kept  and  that  of  the  external  air  expressed  in  degrees 
Fahrenheit  and  divide  the  product  by  2.1  times  the  difference  between 


226  RADIATING    SURFACE. 

200  and  the  temperature  of  the  room;  this  will  give  the  number  of 
square  feet  of  radiating  surface,  which  in  the  foregoing  example  would 
be  25  6. 

In  the  preparation  of  plans  and  specifications  for  the  heating  of  a 
building  by  hot  water  or  steam,  the  first  thing  to  be  done  is  to  prepare 
a  schedule  showing  for  each  room  and  hall  the  dimensions,  the  number 
of  cubic  feet  of  air  space,  the  amount  of  wall  surface  exposed  to  the 
outer  air  stated  in  equivalents  of  square  feet  of  glass  surface,  and  the 
number  of  cubic  feet  of  air  to  be  supplied  per  hour  if  special  ventila- 
tion is  to  be  provided.  The  exposure  of  the  room — that  is,  the  point 
of  the  compass  towards  which  the  windows  look — whether  it  is  a  corner 
room,  and  whether  it  is  sheltered  from  wind  by  trees,  neighboring 
buildings,  etc.,  should  also  be  noted.  From  these  data,  taken  in  con- 
nection with  the  lowest  external  temperature  to  be  provided  against, 
and  with  a  knowledge  of  the  general  conditions  of  the  locality  as  to 
prevailing  winds  in  winter,  exposure,  etc.,  there  is  to  be  calculated  for 
each  room  the  number  of  square  feet  of  radiating  surface  of  the  tem- 
perature which  it  is  proposed  to  use  to  maintain  the  temperature  of  the 
room  at  the  point  at  which  it  is  desired  to  keep  it  during  the  coldest 
weather. 

This  will  of  course  give  an  excess  of  radiating  surface  over  that 
which  will  be  needed  in  moderate  weather,  and  special  arrangements 
must  be  made  to  meet  this  difficulty,  as  will  be  explained  hereafter. 

The  amount  of  heating  surface  required  for  each  room  is  that  re- 
quired to  make  good  the  loss  by  radiation  from  the  walls  of  the  room 
plus  the  loss  due  to  convection  of  heat  by  the  air  admitted  to  and 
escaping  from  it,  and  is  computed  from  formulae  deduced  from  the 
laws  governing  the  cooling  of  heated  bodies. 

A  heated  body,  like  a  steam  pipe  or  radiator,  if  placed  in  an  open 
space  where  the  air  can  circulate  freely  around  it,  parts  with  its  heat 
by  radiation  and  by  convection  through  the  air.  For  such  a  body,  the 
loss  of  heat  from  which  is  constantly  replaced  by  the  steam  passing 
through  it,  so  that  its  temperature  may  be  taken  as  constant,  the  for- 
mulae given  by  Peclet  when  the  temperature  of  the  room  is  about 
12°  C.  and  of  the  pipe  about  100°  C.,  are: 

(a)  Loss  by  radiation  =  R  =  Kt  (i   -f  0.0056*),  K  being  a  co- 
efficient depending  on  the  nature  of  the  surface  and  /  the  excess  of 
temperature  of  the  pipe;  and 

(b)  Loss  by  air  convection  —  A  —  K't  (i  -f-  0.0075*)  K'  being 
a  co-efficient  depending  on  the  form  and  dimensions  of  the  body  and  /. 
the  excess  of  temperature. 


RADIATING    SURFACE.  227 

For  cast-iron  surfaces  formula  (a)  becomes 

(c)  R  =  124. 'l2.  Ka"  (ae —  i),  in  which  /'  is  the  temperature  of 
the  locality,  a  —  1.0077,  and  K  —  3.17. 

From  these  formulae,  taken  in  connection  with  the  tables  of  values 
of  the  co-efficients  K  and  K',  have  been  prepared  such  tables  as  those 
given  in  the  treatise  of  Box  on  heat  and  in  Hood's  treatise  on  warming. 

These  formulae  and  tables  are  never  used  in  calculating  the  amount 
of  radiating  surface  required  for  different  rooms  and  buildings,  much 
shorter  and  simpler  rules  being  employed,  and  no  attempt  being  made 
to  secure  just  enough  radiating  surface  and  no  more,  but  an  extra 
allowance  being  made  to  make  sure  that  there  shall  be  enough. 

The  common  rule-of-thumb  method  of  most  workmen  in  the 
steam-heating  business  is,  where  the  external  temperature  does  not  fall 
below  zero,  to  make  an  average  allowance  of  i  square  foot  of  radiat- 
ing surface  to  each  100  cubic  feet  of  space  to  be  heated,  and  then  to 
increase  or  decrease  in  different  rooms,  according  to  their  exposure,  etc. 
Hood's  rules  of  this  kind  for  dwelling  rooms  call  for  about  12  square 
feet  of  steam  radiating  surface,  or  16  square  feet  of  hot-water  heating 
surface  per  1,000  cubic  feet  of  space,  to  maintain  a  temperature  of 
70°  F.  with  the  external  air  at  10°  F.  The  American  practice — to  heat 
from  zero  to  70°  F.  with  low-pressure  steam — gives  for  dwelling  houses 
with  indirect  radiation  about  i  square  foot  of  radiating  surface  to  from 
40  to  60  cubic  feet  of  space,  according  to  exposure:  for  large  office 
buildings,  hotels,  etc.,  mostly  direct  radiation,  i  square  foot  of  radiat- 
ing surface  to  75  cubic  feet  of  space:  and  for  large  halls  and  churches, 
i  square  foot  of  radiating  surface  to  from  90  to  120  cubic  feet  of 
space.  Such  calculations  are,  however,  only  useful  for  preliminary 
rough  estimates  as  to  cost,  etc. 

In  prescribing  the  size  of  a  furnace  or  stove,  i  square  foot  of  its 
heating  surface  is  usually  taken  as  equal  to  6  square  feet  of  steam- 
heated  radiator,  or  to  heating  about  300  cubic  feet  of  space. 

For  the  final  calculations,  where  great  accuracy  is  not  desired, 
several  simple  formulae  are  in  common  use.  Probably  those  most  often 
employed  by  the  best  class  of  steam-heating  engineers  in  the  United 
States  are  those  given  by  Mr.  Baldwin  in  his  well-known  writings  on 
steam  heating,  and  these  are  as  follows  : 

I.  To  obtain  the  amount  of  radiating  surface  required  for  a  given 
room  to  compensate  for  heat  lost  b^c  radiation  from  windows,  doors 
and  walls.  Take  the  difference  in  temperature  in  degrees  Fahrenheit 
between  the  lowest  outside  temperature  to  be  provided  for  and  the 
temperature  at  which  the  room  is  to  be  kept,  and  divide  it  by  the 


228  RADIATING    SURFACE. 

difference  in  degrees  Fahrenheit  between  the  temperature  of  the  steam 
pipes  and  the  temperature  at  which  the  room  is  to  be  kept.  Multiply 
the  quotient  thus  obtained  by  the  number  of  square  feet  of  glass  plus 
the  number  of  square  yards  of  external  wall  surface  in  the  room  and  the 
product  will  be  the  number  of  square  feet  of  radiating  surface  required. 
Suppose,  for  example,  that  we  have  a  room  which  has  36  square 
feet  of  window-glass  surface  and  20  square  feet  of  external-wall  surface 
besides  the  windows,  that  is  to  be  kept  at  a  temperature  of  70°  F. 
when  the  external  temperature  is  10  degrees  below  zero,  and  that  it  is 
to  be  heated  by  direct  radiators  supplied  with  low-pressure  steam, 
which  radiators  may  be  taken  as  having  a  temperature  of  210°  F. 

Then,  -  -   x  56  =  32,  which  is  the  number  of  square  feet  of  radiating 

140 

surface  required.  But  this  does  not  provide  for  any  leakage  of  air 
through  cracks  and  crevices  or  for  any  change  of  air  by  ventilation. 
In  the  above  example  it  is  supposed  that  the  external  walls  are  of 
brick,  plastered,  such  walls  having  from  one-ninth  to  one-tenth  the 
power  of  transmitting  heat  which  ordinary  window  glass  has,  and  hence 
we  reckon  i  square  yard  or  9  square  feet  of  wall  as  equal  to  i  square  foot 
of  glass.  If  the  lowest  external  temperature  to  be  provided  for  be 
taken  as  zero  Fahrenheit,  we  may  assume  that  half  a  square  foot  of 
radiating  surface  at  210°  F.  will  be  required  for  each  square  foot  of 
glass  or  square  yard  of  external  wall. 

We  do  not  take  into  account  the  internal  walls  in  this  calculation, 
because  we  assume  that  they  are  next  to  heated  rooms  or  halls,  but  if  this 
is  not  the  case  they  should  be  reckoned  as  external  walls.  Having  thus 
obtained  the  amount  of  radiating  surface  required  to  compensate  for  loss 
of  heat  through  windows  and  walls,  the  next  thing  is  to  calculate  the 
amount  of  radiating  surface  which  will  be  needed  to  heat  the  cold  air 
coming  into  the  room,  or,  in  other  words,  to  supply  the  heat  carried 
out  of  the  room  by  the  escape  of  warm  air. 

II.  For  air  heating  the  rough  formula  is,  multiply  the  number  of 
cubic  feet  of  air  per  hour  by  the  number  of  degrees  Fahrenheit  which 
it  is  to  be  heated  and  divide  the  product  by  12,500.  The  quotient  is 
the  number  of  square  feet  of  radiating  surface  required.  For  example: 
in  the  room  above  referred  to,  let  us  suppose  its  cubic  contents  to  be 
1,700  cubic  feet,  that  it  is  on  the  side  of  the  building  exposed  to  win- 
ter winds,  and  that  the  usual  amount  of  leakage  around  windows  and 
doors  exists;  then  an  amount  of  air  equal  to  that  contained  in  the 

room  will  probably  pass  through  it  in  an  hour,  and  —  —  n 


RADIATING    SURFACE.  229 

nearly,  which  added  to  32  gives  43  square  feet  as  the  amount  of  radi- 
ating surface  required  in  this  case,  where  there  is  no  special  ventila- 
tion. This  is  equivalent  to  adding  one-third  to  the  radiating  surface 
to  provide  for  leakage,  and  in  this  case  gives  about  i  square  foot  of 
radiating  surface  to  40  cubic  feet  of  space.  Now,  let  us  suppose  that 
the  room  is  to  be  ventilated  at  the  rate  of  6,000  cubic  feet  per  hour, 
that  is,  that  the  air  in  the  room  is  to  be  changed  over  three  times  an 
hour  to  provide  for  its  constant  occupancy  by  two  persons.  Then 

-^          —  =  38.4,  which  added  to  32  gives,  in  round  numbers,  70 
12,500 

square  feet  of  radiating  surface  required.  In  this  case  the  incoming 
cold  air  would  probably  be  admitted  through  the  radiators,  which 
would  be  arranged  on  either  the  indirect  or  the  direct-indirect  systems. 
It  will  be  seen,  therefore,  that  to  heat  a  room  by  the  indirect  system, 
which  necessitates  ventilation,  requires  nearly  twice  the  amount  of  the 
radiating  surface  which  would  answer  if  the  room  was  heated  by 
direct  radiators  only,  with  no  change  of  air  except  that  due  to 
leakage. 

As  another  example,  let  us  take  a  24-bed  ward  in  a  brick  hos- 
pital located  where  a  temperature  of  20  degrees  below  zero  is  to  be 
provided  for,  the  internal  temperature  to  be  70°  F.  We  will  assume 
that  this  ward  contains  24,000  cubic  feet,  that  it  has  288  square  feet  of 
window-glass  surface  and  241  square  yards  of  external-wall  surface, 
and  that  under  ordinary  circumstances  the  supply  of  air  is  to  be  3,600 
cubic  feet  of  air  per  hour  per  bed,  or  a  total  of  86,400  cubic  feet  of  air 
per  hour.  To  supply  the  loss  of  heat  through  walls  and  windows,  we 

shall  need  -   —X  (288  -|-  241)  =  0.643  X  529  =  340  square  feet  of  radi- 
140 

ating  surface.     To  heat  86,400  cubic  feet  of  air  from   20°  F.  to  70°  F. 

86,400X00 

would  require  -  -  =  622   square   feet    of    radiating    surface. 

12,500 

Theoretically,  then,  340  -{-  622  =  962  square  feet  of  radiating  surface 
would  be  required  to  keep  this  ward  thoroughly  heated  and  ventilated 
in  the  coldest  weather,  which  would  be  at  the  rate  of  i  square  foot  of 
radiating  surface  to  25  cubic  feet  of  space  heated.  Practically,  it  would 
be  unnecessary  to  provide  so  much  as  this,  partly  because  the  heated 
air  will  supply  part  of  the  loss  by  walls  and  windows,  partly  because 
in  such  a  climate,  such  a  building  would  have  hollow  walls  and  double 
windows,  which  would  much  lessen  the  loss  of  heat,  and  partly  be- 
cause when  the  external  temperature  fell  below  zero  a  less  amount  of 
air  supply  would  give  sufficient  ventilation  for  the  comparatively  short 


230  RADIATING    SURFACE. 

periods  of  such  extreme  cold.  About  700  square  feet  of  radiating  sur- 
face on  the  direct-indirect  system  would  be  sufficient  for  such  a  ward 
if  properly  distributed  beneath  the  windows. 

The  writer  of  a  series  of  articles  on  hot-water  heating,  recently 
published  in  the  Builder,  says  that  the  best  mode  of  calculating  the 
heating  surface  required  is  to  base  it  on  cubic  contents,  and  that  the 
allowing  so  many  cubic  feet  of  air  per  person  is  objectionable  because 
the  number  of  persons  has  no  relation  to  the  size  of  the  apartment 
since  a  small  lecture  room  might  have  200  people  in  it  while  a  private 
reception  room  might  be  nearly  as  large  and  yet  not  have  more  than 
20  occupants.  Even  calculations  based  on  wall  and  window  surface, 
he  thinks,  are  not  so  good  as  those  based  on  cubic  contents.  If  in- 
struction of  this  kind  is  given  in  such  a  journal  as  the  Builder,  it  is 
no  wonder  that  the  ventilation  of  buildings  is  bad.  The  fact  is,  that 
the  number  of  persons  which  the  room  is  intended  to  accommodate 
determines  the  amount  of  air  which  is  to  be  supplied,  and  the  amount 
of  air  to  be  supplied  in  cold  weather  is  a  predominating  factor  in  deter- 
mining the  amount  of  heat,  and  therefore  the  amount  of  heating  sur- 
face required;  while  next  to  this  in  importance  comes  the  amount  of 
wall  and  window  surface  and  relative  exposure  to  winds,  the  cubic 
contents  being  of  least  importance  of  all  in  the  great  majority  of  cases. 

The  table  given  by  the  above-mentioned  writer  is  of  interest  as 
indicating  present  English  practice  in  hot-water  heating.  It  assumes 
that  the  temperature  of  the  water  in  the  pipes  is  180°  F.,  that  the 
lowest  external  temperature  is  20°  F.,  and  that  a  foot  length  of 
4-inch  pipe  gives  i  square  foot  of  surface. 

It  will  be  observed  that  the  temperatures  specified  for  living 
rooms  are  lower  than  those  required  in  the  United  States,  that  the 
assumed  lowest  temperature  of  the  external  air  is  at  least  20  degrees 
higher  than  that  usually  taken  as  a  basis  of  calculation  in  this  country, 
and  that  the  size  of  pipe  is  an  inch  larger  than  that  ordinarily  used 
for  indirect  hot-water  heaters  here. 

When  the  schedule  of  rooms  has  been  filled  out  so  as  to  show  for 
each  room  the  amount  of  radiating  surface  which  is  to  be  provided,  and 
its  character — i.  e.,  whether  direct,  indirect  or  direct-indirect,  including 
also  the  surface  of  coils  for  accelerating  air  currents  in  flues,  if  such  are 
to  be  used,  the  next  step  is  to  indicate  upon  the  floor  plans  the  position 
of  each  of  the  radiators,  and  its  size,  as  a  basis  for  fixing  the  size  and 
position  of  the  pipes  by  means  of  which  they  are  to  be  connected  with 
the  boiler  so  as  to  insure  circulation.  The  location  of  direct  radiators 
in  a  room  must  be  governed  mainly  by  the  uses  of  the  room  and  the 


RADIATING    SURFACE. 


231 


position  of  articles  of  furniture  in  it.  So  far  as  the  heating  of  the  room 
is  concerned  it  is  a  little  better  that  the  radiator  should  be  near  the 
outer  wall,  especially  if  this  is  to  be  the  windward  side  of  the  house  in 
cold  weather;  but  for  most  rooms  the  precise  location  does  not  matter 
much  so  far  as  warmth  is  concerned,  and  other  things  being  equal,  it 
may  be  arranged  to  suit  connections  with  mains  and  risers  so  that 
these  shall  be  short  lines  and  with  proper  grades.  Direct-indirect  radia- 
tors will  usually  be  placed  beneath  the  windows.  The  indirect  radiators 
will  usually  be  placed  in  the  basement  or  cellar,  and  may  be  divided 
into  two  classes,  those  placed  immediately  beneath  the  rooms  to  be 
heated,  and  those  placed  at  a  distance  and  requiring  mechanical  power 
to  control  the  movement  of  air  through  them.  The  most  usual  arrange- 
ment is  to  place  them  just  below  the  rooms  to  be  heated  and  to  have  the 


Quantity  of  4-Inch  Pipe 

Some  of  the  Uses  for  Which  the  Heat  May 
be  Required. 

Temperature 
Required. 

Required  for  Eyery 
1,000  Cubic  Feet  Capacity 
in  a  Brick-Built  Room. 

Windows  as  Usual. 

Deg.  F. 

Feet. 

50                                6 

Coach  houses,  etc. 

55 

7 

Work  rooms,  etc. 

60                            8  to  g 

Churches,  bedrooms 

65 

10 

Living  rooms. 

70 

35 

'Drying  room,  herbs,  paper,  etc. 

75 

45 

-  Free  ventilation. 

80 

60 

This  heat  when  empty  and  dry. 

IOO 

no 

'Drying  rooms  for  moist  articles, 
dry  work,  etc. 

laun- 

no 

140 

Full  ventilation. 

1  20 

1  80 

This  heat  when  empty  and  dry. 

flues  leading  from  them  constructed  in  the  outer  wall.  To  insure  good 
results  each  room  should  have  its  own  flue,  its  own  radiator,  and  its 
own  separate  fresh-air  supply  for  that  radiator,  but  it  is  often  difficult 
and  somewhat  expensive  to  secure  this.  If  there  are  three  or  more 
stories  to  be  supplied,  and  the  rooms  are  not  large,  there  may  be  some 
little  trouble  in  getting  the  requisite  number  of  flues  in  the  wall,  and 
still  more  trouble  in  getting  separate  radiators  for  each  flue.  Many 
men  in  planning  for  indirect  radiation  will  give  one  common  radiator 
for  three  or  four  flues  and  attempt  to  check  the  tendency  of  the  flue 
going  to  the  upper  story  to  take  more  than  its  fair  share  of  air  by  put- 
ting a  diaphragm  at  its  mouth  or  "throttling"  it.  In  good  work  this 
taking  of  flues  from  the  same  radiator  for  rooms  on  different  stories 


232  BOILERS. 

should  never  be  done,  and  it  is  never  necessary  to  do  it.  The  openings 
of  the  flues  may  be  close  together,  separated  by  but  a  single  brick,  so 
that  one  or  both  of  the  radiators  must  be  set  back  and  connected  with 
the  flue  by  a  duct  of  galvanized  iron  leading  from  its  case;  but  while 
this  increases  the  cost  a  little,  it  should  be  insisted  on  by  the  heating 
engineer  and  by  the  architect. 

Having  decided  approximately  on  the  location  and  size  of  the 
radiators,  the  next  thing  to  be  considered  is  the  location  and  size  of 
the  mains  and  boiler.  For  all  dwelling  houses,  and  for  the  majority  of 
buildings,  a  low-pressure  apparatus,  the  condensed  water  from  which 
returns  to  the  boiler  by  gravity  without  the  use  of  pumps  is  what  is 
most  frequently  used.  By  a  low-pressure  apparatus  is  meant  one  which 
will  give  a  circulation  of  steam  throughout  with  a  pressure  of  not  to 
exceed  one  pound  per  square  inch  above  the  atmospheric  pressure  at 
the  boiler  and  the  maximum  pressure  in  the  boiler  of  which  shall  never 
exceed  10  pounds.  To  secure  this  sufficiently  large  supply  and  return 
pipes  are  essential,  and  to  secure  the  gravity  return  the  boiler  must  be 
set  so  far  below  the  level  of  all  the  radiators  as  to  permit  the  return  of 
the  condensed  water  by  the  return  pipes  sloping  constantly  towards  the 
boiler  with  an  easy  grade.  To  prevent  snapping  and  crackling  noises 
within  the  pipes  it  is  desirable  that  their  grade  should  be  such  that  the 
condensed  water  will  always  flow  in  the  same  direction  as  the  current 
of  steam;  hence  the  supply  mains  should  rise  as  soon  as  possible  after 
leaving  the  boiler  to  the  highest  point  to  which  it  is  necessary  to  carry 
them,  and  from  this  point  should  begin  to  fall  to  the  most  distant  point 
at  which  connection  is  to  be  made  with  the  return  pipe,  which  from 
thence  is  to  slope  towards  the  boiler.  In  large  pieces  of  work  it  is 
often  impossible  to  arrange  the  pipes  in  this  way  and  then  it  becomes 
necessary  to  use  traps  and  perhaps,  also,  a  pump  or  pumps. 

There  are  many  kinds  of  steam-heating  boilers  in  the  market  and 
new  patterns  are  being  added  every  year.  For  all  steam-heating  plants 
requiring  1,500  or  more  square  feet  of  radiating  surface,  none  of  them 
are  superior  to  the  ordinary  horizontal  flue  boiler.  For  smaller  plants^ 
and  under  circumstances  where  horizontal  space  for  the  boiler  is  lim- 
ited, it  may  be  better  to  use  some  form  of  vertical  boiler  with  drop 
tubes. 

The  size  of  the  boiler  required  is  fixed  by  the  amount  of  radiating 
surface  to  be  supplied,  care  being  taken  that  it  is  in  excess  rather  than 
too  small.  In  localities  where  the  external  temperature  may  at  times 
be  20°  below  zero  F.,  as  in  Canada  and  the  northern  part  of  the  United 
States,  a  square  foot  of  heating  surface  in  the  boiler  will  be  required  to 


BOILERS.  233 

each  5  square  feet  of  radiating  surface  to  provide  for  all  emergencies. 
Where  the  external  temperature  is  never  below  zero  F.,  i  to  6  or  6y? 
is  sufficient.  The  proportion  of  grate  surface  to  boiler  surface  varies 
greatly  in  different  boilers,  from  i  to  25  to  i  to  50  or  more. 

The  size  of  boilers  is  often  stated  by  bidders  and  contractors  as 
being  of  so  many  horse-power,  but  this  is  an  indefinite  and  unsatis- 
factory mode  of  stating  it.  What  is  commonly  understood  by  a  horse- 
power is  a  force  equal  to  550  foot-pounds  per  second.  The  French 
horse-power  is  75  kilogrammeters  =  542  foot-pounds  per  second. 
The  common  English  horse-power  is  that  produced  by  the  evaporation 
of  a  cubic  foot  of  water  to  steam,  or  about  70,000  thermal  units,  but  it 
has  been  defined  as  equal  to  the  evaporation  of  30  pounds  of  water 
from  2i2Q  F.,  which  would  only  require  about  29,000  thermal  units. 
Mr.  Mills  estimates  one  horse-power  as  equal  to  the  supply  of  heat  to 
90  square  feet  of  radiating  surface,  or  the  giving  off  of  a  little  over  10 
cubic  feet  of  steam  per  minute.  On  this  basis  an  1 1  horse-power  boiler 
would  be  required  for  1,000  square  feet  of  radiating  surface. 

With  regard  to  sizes  of  mains  for  low-pressure  steam  work,  the 
usual  practice  is  to  allow  i-inch  pipe  for  100  square  feet  of  radiating 
surface  or  less;  i^-inch,  for  from  100  to  225;  2-inch,  from  225  to  . 
450;  2^-inch,  from  450  to  700;  3-inch,  from  700  to  1,200;  3^-inch, 
from  1,200  to  1,500;  4-inch,  from  1,500  to  1,900;  4^-inch,  from  1,900 
to  2,300;  and  5-inch,  from  2,300  to  2,800. 

Mr.  Baldwin's  formula  is  that  the  diameter  of  the  main  in  inches 
should  equal  one-tenth  of  the  square  root  of  the  number  of  square 
feet  of  radiating  surface  which  it  is  to  supply.  In  calculating  by  this 
rule  the  regular  commercial  sizes  of  pipes  should  be  remembered  as 
increasing  in  diameter  by  half  inches  up  to  5-inch  pipe,  and  above  that 
by  inches  up  to  15  inches. 

The  formulae  for  sizes  of  chimney  flues  in  connection  with  boilers 
are  given  in  Chapter  VIII. 

The  only  objection  to  having  the  steam  mains  somewhat  larger 
than  is  necessary  is  the  slightly  increased  cost  of  the  pipe — they  addr 
nothing  to  the  cost  of  running  the  apparatus.     The   pipes  for  return 
of  condensed  water  may  be  a  size  or  two  smaller  than  the  correspond- 
ing steam  pipes. 

For  comparatively  large  steam-heating  plants,  what  is  sometimes 
called  the  hot-blast  system  is  recommended  by  some  engineers.  In 
this  all  the  heating  surfaces  are  as  far  as  possible  brought  together  in 
a  special  chamber  or  duct  and  the  cold  air  is  forced  or  drawn  over 
these  surfaces  by  a  fan  or  blower,  after  which  it  is  distributed  by  ducts 


234  HOT    BLAST. 

and  flues  to  the  different  rooms.  This  is  economical  as  to  piping,  and 
if  forced  ventilation  by  fans  is  to  be  used  is  in  some  cases  a  good 
plan,  especially  for  buildings  which  are  to  be  occupied  but  a  few 
hours  at  a  time,  such  as  churches,  assembly  halls  and  large  office 
buildings.  For  buildings  which  are  to  be  continuously  occupied,  and 
especially  for  hospitals,  it  is  not  so  advantageous,  because  it  is  diffi- 
cult to  so  regulate  the  temperature  of  the  incoming  air  as  to  produce 
the  differences  in  different  rooms  which  are  often  desirable.  It  is 
true  that  by  the  use  of  properly  arranged  mixing  valves  with  separate 
cold-air  inlets  at  the  bottom  of  each  flue  this  objection  might  be 
greatly  lessened,  if  not  done  away  with.  This  system  may  also  be 
combined  with  the  having  small  radiators  at  the  bottom  of  each  flue, 
adjusted  to  produce  an  increase  of  temperature  of  not  more  than  20° 
F.,  the  air  being  delivered  to  them  from  the  central  coils  at  a  uni- 
form temperature  of  about  55°  F. 

In  dwelling  houses,  offices,  hospitals,  and  the  majority  of  inhab- 
ited rooms,  in  proportioning  the  heating  surfaces  no  account  is  taken 
of  the  heat  given  off  by  the  bodies  of  the  occupants  or  by  the  means 
used  for  illumination.  In  rooms  where  a  large  number  of  people  are 
to  be  gathered,  and  which  are  to  be  occupied  at  night  with  many  gas 
lights,  the  additional  amount  of  heat  thus  produced  must  be  con- 
sidered, not  so  much  with  reference  to  the  amount  of  radiating  surface 
to  be  provided,  since  this  will  at  times  be  called  upon  to  do  its  work  in 
the  day  time  and  when  the  room  is  nearly  empty,  as  with  reference  to 
the  means  of  cutting  off  a  part  of  this  radiating  surface  or  of  admitting 
more  cold  air,  or  both,  when  the  room  is  crowded  and  lighted.  This 
applies  to  assembly  halls,  school  rooms,  churches,  theaters  and  opera 
houses,  etc. 

The  heat  produced  by  an  ordinary  candle  is  100  calories  per  hour; 
that  from  an  ordinary  gas  burner  is  1,430  calories  per  hour;  one  gas 
burner  using  about  5  cubic  feet  of  gas  per  hour  requires  60  cubic  feet 
of  air  for  combustion. 

The  exhaust  steam  from  an  engine  can  often  be  usefully  employed 
for  heating  purposes.  For  this  purpose  a  back-pressure  valve  is  placed 
in  the  exhaust  pipe,  and  a  pipe  is  taken  from  below  this  valve  through 
a  grease  separator  to  the  main  supplying  the  radiators.  These  must  be 
arranged  for  a  low-pressure  system,  and  the  return  must  go  to  a  tank 
from  which  the  condensed  water  can  be  pumped  by  a  special  pump 
into  the  boiler  if  so  desired.  Usually  a  direct  live-steam  connection 
between  the  boiler  and  the  heating  system  will  also  be  required  to  pro- 
vide for  heating  when  the  engine  is  not  at  work. 


RADIATORS.  235 

Where  there  are  large  boiler  and  engine  plants,  as  at  central  elec- 
tric light  stations,  this  use  of  the  exhaust  steam  to  supply  hea't  to 
neighboring  buildings  may  be  an  important  matter. 

There  are  many  patterns  of  radiators  in  the  market  and  the  num- 
ber is  added  to  every  year.  Each  firm  engaged  in  the  construction  of 
heating  apparatus  usually  has  its  own  favorite  form,  and  architects 
commonly  do  not  undertake  to  prescribe  the  particular  pattern  to  be 
used,  either  leaving  the  heating  contractor  to  make  his  own  selection, 
or  directing  that  the  radiators  shall  be  of  such  a  pattern  or  its  equiva- 
lent. We  do  not  propose  to  discuss  the  merits  of  different  forms  of 
heaters  for  indirect  work,  or  of  radiators  properly  so-called.  Those 
who  wish  detailed  information  on  this  subject  will  find  the  best  data  in 
the  second  volume  of  the  valuable  work  of  John  H.  Mills  on  "  Heat: 
Science  and  Philosophy  of  Its  Production  and  Application  to  the 
Warming  and  Ventilation  of  Buildings,  etc,"  Boston,  1890,  in  which  the 
results  of  a  number  of  experiments  made  by  Mr.  Baldwin,  Mr.  Mills 
and  others  are  fully  stated.  In  selecting  radiators,  or  in  examining  a 
completed  piece  of  work  to  determine  whether  the  required  amount  of 
radiating  surface  has  or  has  not  been  furnished,  it  should  be  remem- 
bered that  the  number  of  square  feet  of  such  surface  as  stated  by  the 
manufacturer  for  a  particular  form  of  radiator,  and  known  as  the  com- 
mercial rating,  is  often  in  excess  of  the  true  figure  by  from  10  to  25 
per  cent. 

For  heating  of  air,  as  by  the  so-called  indirect  or  direct-indirect 
radiation,  the  object  is  to  bring  the  cold  air  in  at  the  base,  force  it  to 
come  in  contact  with  the  hot  surface  and  allow  it  to  escape  at  the  top. 
The  heating  is  therefore  not  effected  by  radiation  but  by  conduction, 
and  the  arrangement  of  the  heating  surfaces  calculated  to  produce  the 
best  result  is  altogether  different  from  that  which  is  best  for  true  or 
direct  radiation.  Hence,  for  these  indirect  heaters,  the  value  of  an  ex- 
tended surface  obtained  by  projecting  knobs  or  pins,  as  in  the  well- 
known  Gold's  pin  radiator,  or  by  winding  the  pipes  with  wire,  is  great, 
while  for  direct  radiators  it  is  comparatively  small. 

Figure  24  shows  one  way  of  bringing  in  the  air  to  the  base  of  a 
direct-indirect  radiator.  The  opening  of  the  fresh-air  duct  Z>,  is  regu- 
lated by  a  damper,  and  when  this  is  closed  the  apparatus  becomes  a 
direct  radiator. 

Such  closure  often  becomes  absolutely  necessary  when  the  direc- 
tion of  the  wind  is  such  that  the  radiator  is  on  the  leeward  side  of  the 
building,  to  prevent  the  passage  of  air  from  the  room  outward  through 
what  is  intended  to  be  the  inlet  duct. 


236 


RADIATORS. 


Figure  25  shows  a  form  of  radiator  intended  to  allow  the  admis- 
sion of  cold  fresh  air  at  all  times  without  giving  rise  to  the  danger  of 
freezing  water  which  may  have  accumulated  in  the  bottom  through 
leakage  or  improper  setting  of  the  valves.  This  was  devised  by  Mr. 
Baldwin  for  the  Moses  Taylor  Hospital,  and  the  principle  may  be 
applied  to  any  vertical  radiator. 

Immediately  above  each  ordinary  vertical  tube  of  the  radiator  is  a 
short  tube  a,  through  which  the  warm  air  from  the  steam  tube  must 
pass  to  escape  through  the  fretwork  at  the  top.  The  warm  air,  in 


PIG.  24. 


passing  through  the  tubes  a  (which  tubes  may  be  of  any  desired 
length),  warms  them  to  from  120°  to  140°  F.  The  entering  cold  air, 
as  indicated  by  the  arrows,  passes  between  these  tubes  and  beneath 
the  plate  b  to  the  froiit  half  of  the  radiator  before  it  can  mingle  with 
the  air  from  the  steam-heated  pipes.  A  plate  similar  to  ^,  and  extend- 
ing over  the  whole  size  of  the  radiator,  confines  the  lower  ends  of  the 
pipes  a,  and  prevents  the  entering  air  from  falling  among  the  steam 
pipes.  In  the  front  of  the  entablature,  as  shown  by  the  plan,  the 
tubes  a  terminate  at  the  level  of  the  plate  £,  and  about  three-quarters 
of  an  inch  below  the  fretwork.  This  permits  the  air  that  comes 
through  the  tube  (warm),  and  the  air  that  passes  between  the  plates 


RADIATORS. 


237 


and  the  pipes  a  (slightly  warm),  to  mingle  as  they  pass  through  the 
fretwork,  and  prevents  the  ingress  of  air  that  is  cold  into  the  room. 
It  is  also  claimed  that  a  reversion  of  the  current,  whereby  the  warm 
air  may  pass  out  of  doors,  cannot  exist. 

In  specifying  a  particular  patented  form  of  radiator,  or  one  made 
by  and  obtainable  from  one  firm  only,  it  should  be  borne  in  mind  that 


FIG.  25. 


10  or  15  years  hence  it  may  be  very  difficult  to  obtain  these  radiators, 
or  parts  of  them,  for  purposes  of  alteration  or  repairs.  It  is  not  in 
accordance  with  the  best  interests  of  the  owner  of  the  plant — though 
it  may  be  good  for  the  radiator  trade — that  he  should  be  thus  limited 


238  HOT-WATER    HEATING. 

in  his  future  work,  and  the  safest  thing  for  him  is  to  use  radiators 
constructed  of  ordinary  cast  or  wrought-iron  pipe,  of  which  there 
always  are,  and  probably  will  continue  to  be,  standard  sizes  in  the 
market. 

HEATING    BY    HOT    WATER. 

The  advantages  and  disadvantages  of  hot-water  heating  apparatus 
have  been  in  part  indicated  above.  The  use  of  water  as  a  vehicle  for 
the  conveyance  or  storage  of  heat  has  long  been  known,  but  until  re- 
cently it  has  been  comparatively  little  used  in  this  country,  except  for 
heating  greenhouses,  where  the  constancy  and  regularity  of  the  heat, 
which  it  produces  with  comparatively  little  attendance,  are  of  special 
importance.  It  is  used  in  some  of  the  large  Government  buildings  and 
in  the  Johns  Hopkins  Hospital  in  Baltimore,  and  recently  is  being 
more  employed  for  the  better  class  of  dwelling  houses.  The  rules 
given  above  for  scheduling  rooms,  etc.,  apply  also  to  the  preparation 
of  plans  and  specifications  for  hot-water  heating,  but  the  calculation 
of  the  amount  of  radiating  surface  required  is  based  upon  somewhat 
different  formulae. 

In  heating  by  a  low-pressure  hot-water  system  the  average  maxi- 
mum temperature  of  the  water  may  be  taken  as  140°  F.,  so  that  the 
radiating  surfaces  will  be  about  70°  F.  lower  than  those  which  are 
heated  by  steam,  and  hence  must  be  increased  proportionately.  In 
hot-water  heating  the  greater  part  of  the  work  is  usually  done  by  in- 
direct radiation,  and  the  calculations  are  to  be  made  with  reference  to  air 
suppty  primarily,  with  secondary  corrections  for  loss  of  heat  by  radia- 
tions from  windows  and  walls.  There  are  various  forms  of  radiators 
for  hot  water,  as  there  are  for  steam,  but  coils  of  3-inch  cast-iron  pipe 
are  as  good  as  any  other  for  indirect  radiators,  and  give  a  convenient 
basis  for  calculation,  since,  including  sockets,  etc.,  100  feet  run  of  3- 
inch  pipe  give  about  TOO  square  feet  of  radiating  surface.  Mr.  Charles 
Hood,  who  is  the  chief  English  authority  on  hot-water  heating,  bases 
most  of  his  calculations  upon  radiation  from  4-inch  cast-iron  pipe,  but 
the  smaller  size  is  preferred  in  this  country  because  it  has  a  larger 
radiating  surface  in  proportion  to  the  amount  of  water  contained,  and 
therefore  insures  a  quicker  circulation.  It  will  not  do  to  use  less  than 
3-inch  pipes  in  most  of  the  radiators,  because  the  friction  increases 
rapidly  with  the  reduction  of  the  diameter  of  the  pipe,  and  thus  im- 
pedes the  circulation  and  diminishes  the  effect.  Where  it  is  specially 
important  to  guard  against  the  effects  of  negligence  in  firing,  as  in  a 
greenhouse,  and  where,  therefore,  a  large  body  of  hot  water  is  needed 


HOT-WATER    HEATING. 


239 


as  a  sort  of  storehouse  of  heat,  4-inch  pipes  maybe  usefully  employed, 
but  not  otherwise. 

Mr.  Hood's  calculations  as  to  the  amount  of  air  to  be  warmed  are 
based  on  a  supply  of  from  3/^2  to  5  cubic  feet  per  minute  for  each  per- 
son in  habitable  rooms,  which  is  hardly  one-tenth  of  the  amount  re- 
quired for  the  preservation  of  health  and  comfort.  He  also  allows  i % 
cubic  feet  of  air  per  minute  for  each  square  foot  of  glass  which  the 
building  contains,  and  having  thus  calculated  the  quantity  of  air  to  be 
heated  per  minute,  he  gives  the  following  rule  for  finding  the  amount 
of  pipe  required  to  heat  it : 

"Rule. — Multiply  125  by  the  difference  between  the  temperature 
at  which  the  room  is  purposed  to  be  kept  when  at  its  maximum,  and 
the  temperature  of  the  external  air,  and  divide  this  product  by  the 
difference  between  the  temperature  of  the  pipes  and  proposed  tem- 
perature of  the  room,  then  the  quotient  thus  obtained,  when  multiplied 
by  the  number  of  cubic  feet  of  air  to  be  warmed  per  minute  and  this 
product  divided  by  222,  will  give  the  number  of  feet  in  length  of  pipe, 
4  inches  diameter,  which  will  produce  the  desired  effect." 

This  rule  depends  upon  the  fact,  determined  by  experiment,  that 
i  foot  of  4-inch  pipe  will  heat  222  cubic  of  air  i  degree  per  minute, 
when  the  difference  between  the  temperature  of  the  pipe  and  the  air  is 
125  degrees.  To  apply  it  to  3-inch  pipe,  the  quantity  should  be  in- 
creased by  one-third. 

From  this  it  would  follow  that  to  heat  1,000  cubic  feet  of  air  per 
minute,  using  for  this  purpose  3-inch  pipe  at  the  temperature  of 
i8o9  F.,  and  supposing  the  temperature  of  the  external  air  to  be  at 
zero  F.,  there  would  be  required  to  maintain  the  room  at  the  following 
temperatures,  the  amount  of  pipe  set  underneath  each — viz.: 


Temperature  at  which  room  is  to  be  kept  — 

55° 

60° 

65° 

70° 

75° 

Number  of  feet  of  3-inch  pipe  required  for 

each  1,000  feet  of  air  per  minute  supplied. 

330 

375 

424 

477 

536 

Those  who  furnish  hot-water  apparatus  very  rarely  calculate  the 
amount  of  radiating  surface  with  reference  to  the  amount  of  air  to  be 
supplied.  They  proportion  the  amount  of  radiating  surface  to  the 
cubic  space  to  be  heated,  according  to  certain  empirical  formulae,  in 
which  usually  the  question  of  ventilation  is  not  taken  into  account. 

For  example,  to  heat  churches  and  large  public  rooms,  Hood  allows 
i  foot  of  4-inch  pipe  to  each  200  cubic  feet  of  space;  that  is,  5  feet  per 


240 


HOT-WATER    HEATING. 


1,000  cubic  feet.  For  dwellings  he  allows  14  feet  per  1,000;  for  schools 
and  lecture  rooms,  from  6  to  7  feet,  and  for  greenhouses  35  feet  per 
1,000,  and  says  that  these  amounts  have  been  determined  by  actual  trial. 

Mr  Anderson,  in  a  valuable  paper  on  the  emission  of  heat  by  hot- 
water  pipes,  concludes  that  for  ordinary  dwelling  houses,  i  square  foot 
of  surface  is  necessary  to  every  65  cubic  feet,  and  in  a  greenhouse  i 
square  foot  to  every  24  cubic  feet.  These  figures  are  based  on  data 
collected  by  him,  a  specimen  of  which  is  given  in  the  accompanying 
table. 

There  is,  however,  one  very  important  defect  in  the  table — viz.,  it 
gives  us  no  information  as  to  the  amount  of  air  which  passed  over  the 
heating  surface  in  a  given  time.  In  the  school  buildings  there  seems 
to  have  been  no  ventilation  at  all.  It  does  not  seem  to  have  occurred 
to  Mr.  Anderson  that  ventilation  is  of  any  importance  in  connection 
with  heating  problems.  He  remarks  that  "the  heating  surface  neces- 
sary to  warm  a  given  building  depends  on  a  variety  of  circumstances — 
on  geographical  position,  whether  the  house  stands  high  and  exposed 
or  low  and  sheltered,  and  whether  the  average  winter  temperature  is 
high  or  low;  on  the  thickness  and  material  of  walls;  on  the  area  and 
construction  of  windows,  and  so  forth."  All  this  is  true  so  far  as  it 
goes,  but  the  ventilation  is  more  important  than  any  of  the  points  he 
has  named,  and  it  is  curious  to  see  how  totally  he  ignores  it. 

For  American  climates  and  for  details  of  apparatus  the  best  book 
on  this  subject  is  "  Hot-Water  Heating  and  Fitting,"  by  W.  J.  Baldwin, 
New  York.  The  Engineering  Record,  1889.  As  explained  above, 
the  technical  difficulties  to  be  overcome  are  greater  in  the  case 
of  hot-water  than  of  steam  apparatus,  and  require  greater  care  in 
proportioning  areas  of  pipes  and  openings,  in  maintaining  proper 
grades,  etc.,  in  order  to  secure  the  requisite  amount  of  circulation  in 
every  part  of  the  apparatus,  but  with  a  good  system  the  results  are 
very  satisfactory. 

The  provision  of  automatic  means  for  regulating  a  heating 
apparatus  so  as  to  maintain  substantially  the  same  temperature  in  a 
room  or  building  is  sometimes  desirable.  There  are  several  means  of 
doing  this,  some  directly  mechanical  by  the  expansion  or  contraction 
of  a  strip  of  metal,  and  others  acting  by  production  of  an  electric 
current  by  contact.  An  old  form  is  Appold's  apparatus,  shown  in 
Fig.  26.* 

*  Gassiot  (J.  P.)  on  Appold's  apparatus  for  regulating  temperature  and 
keeping  the  air  in  a  building  at  any  desired  degree  of  moisture,  in  Proceed- 
ings, Royal  Society  of  London,  1866-67,  Vol.  XV.,  pp.  144-5. 


HOT-WATER    HEATING. 


24I 


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DESCRIPTION  OF  BUILDING  OR  ROOM. 

LESNEY  HOUSE,  ERITH,  KENT. 

he  whole  house  is  warmed  by  hot  water,  more  espec 
passages,  which  in  the  coldest  weather  can  be  maint£ 
5o  degrees.  The  rooms  all  open  into  the  passages, 
ise  stands  150  feet  above  the  river,  and  is  much  expos 
TUDY.  —  Bow  window  to  the  east.  Hot-  water  pipes  u 
window  seats,  with  three  openings  ?'X4%\  covers 
perforated  zinc,  through  the  walls  to  admit  externa 
through  coils.  Coils  concealed  by  open  cast-iron  v 
constant  current  up  the  chimney.  Only  one  exte 
wall,  namely,  the  bow  window  
INING  ROOM.—  Bow  window,  facing  to  the  north, 
coils  in  all  respects  as  in  the  study.  Another  wir 
faces  to  the  west.  Two  external  walls  
ATH  ROOM.—  One  window,  facing  west;  group  of  ] 
placed  against  inner  wall  opposite  window;  no  comn 
cation  with  the  external  air;  open  chimney;  one  exte 
wall  

EKITH  PUBLIC  ELEMENTARY  SCHOOLS, 
ne-story  brick  buildings,  not  plastered  inside,  stand 
river,  and  sheltered  by  surrounding  houses,  the  i 
ed  up  to  the  collar  tie.  The  coils  of  pipe  are  quite  c 
placed  near  the  walls,  most  of  which  are  external: 
Boys'  school  
Girls'  school  
Infants'  school,  total  
Class  rooms—  A  
B  
Babies'  south  aspect  

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Q    «>•-  H     g 

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((    UNiV 

242 


THERMOSTATS. 


This  instrument  consists  of  a  glass  tube  having  bulbs  at  each  end. 
The  tube  is  filled,  as  also  about  half  of  each  bulb,  with  mercury,  the 
lower  bulb  containing  ether  to  the  depth  of  half  an  inch,  which  floats  on 
the  mercury.  The  tube  is  secured  to  a  plate  of  boxwood,  and  supported 
on  knife  edges,  on  which  it  turns  freely.  At  the  end  of  the  plate,  under- 
neath the  highest  bulb,  is  a  lever  to  which  a  string  is  attached.  This 
string  is  carried,  by  means  of  bell  cranks,  to  the  supply  valve  of  a  gas 
stove  or  the  damper  of  a  furnace. 

The  instrument  acts  in  the  following  manner:  Supposing  the 
stove  to  be  lighted  and  to  have  raised  the  temperature  more  than  is 


FIG.  26. 


required,  the  heat  will  convert  a  portion  of  the  ether  in  the  lower  bulb 
into  vapor.  The  expansion  of  this  vapor  drives  a  quantity  of  the 
mercury  out  of  the  bulb  underneath  it  through  the  tube  into  the  upper 
bulb.  The  end  to  which  the  mercury  has  been  driven  being  thus  ren- 
dered the  heaviest,  falls,  and  motion  being  communicated  by  the  lever 
to  the  string,  this  closes  the  supply  valve  or  damper  of  the  stove  or 
furnace.  Of  course,  if  this  should  be  carried  beyond  the  required  ex- 
tent the  reverse  action  will  take  place. 


THERMOSTATS. 


243 


A  weight  in  the  center  of  the  plate,  the  position  of  which  is  regu- 
lated by  a  milled-head  screw  shown  at  the  side,  serves  to  alter  the 
center  of  gravity  of  the  whole  apparatus.  The  value  of  the  motion 
of  this  weight  being  carefully  ascertained,  a  scale  is  engraved  upon  it. 
By  moving  this  weight,  according  to  a  scale  engraved  on  it,  the  in- 
strument may  be  set  so  as  to  maintain  any  desired  temperature  in  the 
building  in  which  it  is  fixed. 

The  range  of  action  of  the  instrument  is  from  54°  to  66°  F.,  and 
with  a  change  of  temperature  of  i  degree  it  has  the  power  to  raise 
one  ounce  3  inches. 

Of  thermostats  for  controlling  heating  by  means  of  electricity 
there  are  several  kinds  in  the  market.  One  of  these,  operating  by 
means  of  compressed  air,  is  shown  in  Fig.  27  as  applied  in  the  Me- 
chanics Bank  Building,  in  New  York,  and  described  in  The  Engineer- 
ing Record  of  August  9,  1890. 


FIG. 


This  thermostat  may  be  set  to  work  at  any  temperature,  and  is 
claimed  to  operate  satisfactorily  within  a  range  of  i  degree.  The 
figure  shows  the  back  of  the  instrument  that  is  mounted  on  a  brass 
bed  plate  P,  to  which  are  fixed  the  standards  ABB  that  carry  the 
mechanism  and  have  holes  Z,  Z  for  attaching  it  to  the  wall  or  other 
convenient  support.  One  end  of  lever  C  is  connected  to  A  by  the 
pivot  Z>,  and  the  other  end  by  a  screw  F  tapped  through  lug  E. 

The  expansion  bar  /  is  made  of  a  plate  of  brass  and  a  plate  of 
rubber  riveted  together  and  attached  to  lever  C  at  pivot  D. 

The  other  end  of  the  bar  is  free  and  carries  a  platinum  contact 
bar  K.  O  O  O  are  bind  posts  fixed  on  plate  B,  and  receiving  the  cir- 
cuit wires  Q  R  V,  and  the  adjustable  contact  points  L  and  M.  The 
rubber  and  bra»s  in  bar  /expand  and  contract  differently  for  the  same 
differences  of  temperature,  so  that  a  rise  in  temperature  will  make  it 


244  THERMOSTATS. 

bow  out  to  the  (exaggerated)  position  U,  and  throw  K  to  K'  in  con- 
tact with  J/,  thus  completing  the  electric  circuit  from  R  through  Qand 
opening  the  valve. 

A  fall  in  the  temperature  bows  out  7  in  the  opposite  direction  to 
the  (exaggerated)  position  X  and  makes  contact  between  K  and  L, 
thus  completing  the  circuit  from  R  to  Fand  closing  the  valve. 

By  moving  lever  G  along  the  scale  H,  screw  F  is  turned  and 
swings  lever  C  on  its  pivot  D  so  as  to  set  the  bar  K  nearer  to  either 
L  or  J/,  and  make  the  thermostat  operate  at  any  desired  temperature 
within  15  degrees  of  that  originally  provided  for. 


FIG.  28. 


Tis  a  thermometer  with  scale  S  on  the  face  of  plate  P;  the  ther- 
mometer is  entirely  independent  of  the  thermostat  and  in  no  way  con- 
nected with  its  operation,  but  is  attached  to  it  simply  for  convenience. 

The  current  from  the  thermostat  operates  the  electro-pneumatic 
valve,  of  which  Fig.  28  is  a  general  view  and  Fig.  29  is  a  plan  with  the 
top  E  removed. 

The  chamber  D  is  substantially  a  three-way  valve  with  its  ports 
opened  and  closed  by  a  pair  of  electro-magnets.  A,  C  and  B  are  tubes 
to  the  compressed-air  main,  to  the  steam  valve,  and  a  free  vent,  re- 
spectively. C  is  always  open  into  chamber  D.  A  is  open  when  B  is 
closed  and  vice  versa.  N  S  and  JV'  S'  are  electro-magnets.  J  J  are 
armatures  connected  by  cross-piece  K  that  is  pivoted  in  the  center. 


THERMOSTATS. 


245 


Lever  G,  pivoted  at  the  center,  has  its  faces  F  F  covered  with 
rubber,  into  which  the  sharp  edges  of  tubes  A  and  B  sink  and  make 
tight  joints. 

The  arm  /  is  pivoted  to  one  end  of  armature  J  and  carries  the 
contact  roller  H  that  has  its  bearing  on  G  maintained  by  the  spiral 
spring  O.  The  operation  by  the  thermostat,  Fig.  29,  is  as  follows  :  Air 
pressure  is  always  maintained  in  tube  A\  suppose  it  to  be  shut  off  as 
shown  in  Fig.  29,  then  the  vent  B  is  open  and  the  steam  valve  operated 
through  pipe  C  is  open  ;  if  now  the  temperature  rises  a  little  and 


Y 


FIG.  2Q- 


operates  the  thermostat  it  sends  a  current  through  V  and  magnetizes 
the  poles  N'  S',  which  then  attract  the  armatures  J  J  that  revolve  in 
the  direction  P,  and  the  movable  parts  of  the  mechanism  take  the  po- 
sitions shown  by  dotted  lines  ;  lever  G  opens  A  and  closes  JBy  and  the 
pneumatic  pressure  in  C  closes  the  steam  valve.  When  the  tempera- 
ture has  fallen  sufficiently  the  thermostat  changes  the  current  from  V 
(Fig.  27)  to  Q,  which  correspondingly  cuts  it  off  from  electro-magnet 
N'  Sr,  Fig.  29,  and  sends  it  through  electro-magnet  AT  S,  which  then 
attracts  the  armatures  J  J  back  to  the  original  position,  shutting  off  air 
pressure  through  A,  opening  vent  B  and  allowing  the  steam  valve  to  open 
as  pressure  fails  in  C.  L  L  are  contact  springs  that  switch  off  the 


246 


THERMOSTATS. 


current  through  conductors  M  M  as  soon  as  the  armatures  reach  their 
extreme  positions,  thus  cutting  off  the  current  and  saving  the  battery. 

Figure  30  is  a  sectional  view  of  the  steam  valve  and  shows  its 
operation  by  compressed  air  from  tube  C,  Fig.  29.  F  is  the  steam  inlet, 
and  Q  its  outlet  B  is  the  valve  seat  and  A  the  poppet  valve,  whose 
stem  passes  through  a  stuffing  box  E  and  is  fastened  to  a  wooden 
head  H. 

I  is  a  circular  rubber  diaphragm,  clamped  between  the  hemis- 
pherical shell  J  and  the  ring  K.  L  is  a  spiral  spring  that  opens  the 
valve  A  as  shown,  when  there  is  no  pressure  in  chamber  M ;  if  press- 


ure be  admitted  through  C,  the  diaphragm  and  stem  head  will  be  forced 
down  towards  position  H ',  indicated  by  dotted  lines,  and  the  valve  will 
be  closed  and  steam  shut  off  as  long  as  pressure  is  maintained  in  M. 
This  cut  shows  the  valves  as  used  in  this  case,  but  in  some  cases  the 
stem  D  is  continued  to  pass  through  another  stuffing  box  N  and  ter- 
minate in  a  handle  0,  shown  by  dotted  lines,  so  as  to  admit  of  regula- 
tion by  hand  at  the  radiator  independently  of  the  thermostat  system. 
Globe  valves,  gate  valves  and  other  forms  are  also  arranged  in  the 
same  manner. 


CHAPTER  XI. 

SOURCES   OF     AIR     SUPPLY.        FILTRATION     OF     AIR.        FRESH-AIR     FLUES 
AND  INLETS.       BY-PASSES. 

IN  selecting  the  point  or  points  from  which  the  external  air  is  to  be 
taken  for  purposes  of  ventilation,  it  is  usual  to  consider  only  the 
character,  position  and  relations  of  the  heating  apparatus.  In  warm 
weather  it  is  presumed  that  windows,  and  often  doors  will  be  opened, 
and  that  the  air  in  the  immediate  vicinity  of  the  building,  whatever 
may  be  its  impurities,  will  be  admitted  freely.  The  same  is  the  case  in 
cold  weather,  in  heating  by  direct  or  by  direct-indirect  radiation;  what- 
ever air  is  admitted  comes  from  the  immediate  exterior  of  the  building. 

In  heating  by  indirect  radiation  the  air  may  be  taken  in  the  same 
way  from  near  the  ground  in  the  immediate  vicinity  of  the  furnace  or 
of  each  separate  heater,  or  it  may  be  taken  from  a  point,  more  or 
less  elevated  and  more  or  less  distant  from  the  building,  with  a  view 
to  obtaining  the  purest  air  possible.  The  great  objection  to  taking  the 
air  from  near  the  surface  of  the  ground  is  that  it  is  more  liable  to  con- 
tain dust,  especially  when  the  openings  are  directly  on  the  street 
through  a  basement  window,  as  is  very  commonly  the  case  in  cities. 
Where  the  openings  are  over  a  grassed  surface  or  lawn,  as  is  the  case 
in  the  Johns  Hopkins  Hospital  wards,  there  are  no  special  objections 
to  such  a  location. 

If  a  special  single  inlet  for  air  for  a  large  building  is  to  be  pro- 
vided in  connection  with  some  form  of  blower  or  aspiration  system,  it 
may  be  taken  down  through  a  shaft  or  tower  between  20  and  30  feet 
in  height.  Above  this  height  the  air  in  a  city  is  liable  to  be  contami- 
nated by  smoke  and  fumes  of  various  kinds,  and  in  any  case  a  height 
of  25  feet  will  probably  reach  as  pure  a  stratum  of  air  as  can  be  found 
in  the  vicinity.  A  good  example  of  such  air-inlet  towers  is  found  at 
the  Capitol,  at  Washington,  where  one  is  provided  for  each  wing. 

In  connection  with  the  inlets  we  are  sometimes  called  on  to  provide 
for  the  removal  of  particles  of  soot  and  dust  of  various  kinds  suspended 
in  the  air,  or,  in  other  words,  for  the  filtration  of  the  air.  So  far  as 
healthy  persons  are  concerned,  this  matter  of  air  filtration  is  a  point 


248  FILTRATION    OF    AIR. 

of  theoretical  interest  rather  than  of  practical  value,  and  if  we  can  give 
to  such  persons  a  sufficient  supply  of  such  air  as  they  will  breathe  when 
walking  in  the  street,  we  shall  have  done  quite  as  much  as  will  usually 
be  required. 

In  buildings  or  rooms  containing  sick  persons,  or  works  of  art, 
books  in  fine  bindings,  or  other  things  to  which  dust  will  be  injurious, 
and  for  chemical  and  bacteriological  laboratories,  it  will  be  well  to 
provide  means  of  removing  the  dust  from  the  incoming  air.  If  the 
building  be  heated  by  any  form  of  indirect  radiation,  and  the  air  sup- 
ply for  this  purpose  enters  through  a  single  duct,  this  can  be  easily 
done  by  using  strainers  of  coarse  cotton  cloth  or  of  thin  layers  of 
cotton  batting  inclosed  in  wire  frames.  The  chief  points  to  be  borne 
in  mind  in  arranging  such  a  system  of  filters  are,  first,  that  they  form 
a  decided  obstacle  to  the  entrance  of  air,  as  they  give  rise  to  much 
friction,  and  hence,  that  their  area  must  be  six  or  eight  times  that  of 
the  delivery  flues;  and  second,  that  the  filters  must  be  renewed  as  often 
as  they  become  clogged  and  foul. 


A  DUST  ARRESTER 

FIG.  31. 

One  mode  of  arranging  such  a  filter  is  shown  in  the  accompanying 
cut  taken  from  The  Engineering  Record  of  April  13,  1889.  It  consists  of 
a  long  muslin  bag  placed  in  an  enlarged  end  of  the  air  duct.  A  is  the 
air  inlet  through  the  wall  of  the  building  and  C  is  a  bag — as  long  as 
possible  and  made  tapering — with  an  end  of  canvas  D,  to  catch  and 
hold  the  accumulated  dust  and  dirt.  B  is  the  enlarged  part  of  the  air 
duct  to  contain  the  bag,  and  a  door  should  be  provided  at  F  for  the 
purpose  of  removing  the  bag  when  foul  and  putting  in  a  clean  one. 
The  bag  should  be  turned  inside  out  and  washed  and  dried  before 
using  again,  and  two  or  more  bags  should  be  provided  so  as  to  have  a 
clean  one  always  ready.  The  longer  the  bag  is  the  better,  and  if  at 
first  it  seems  to  be  a  little  longer  than  necessary,  from  the  fact  that  it  is 
not  at  once  fully  inflated,  the  inflation  will  increase  as  the  muslin  be- 
comes more  and  more  clogged  with  dirt,  and  a  similar  effect  will  be 
noticed  in  damp  weather.  New  bags  should  be  well  washed  before 


FILTRATION    OF    AIR. 


249 


using,  so  as  to  remove  any  size  or  stiffening  that  there  may  be  in  the 
cloth. 

Figure  32  shows  the  arrangement  of  the  radiators  placed  beneath 
the  windows  in  the  Laboratory  of  Hygiene  of  the  University  of  Penn- 
sylvania, where  it  is  specially  desirable  to  remove  the  dust  from  the 
incoming  air;  A  A,  fresh-air  opening  in  wall  beneath  windows,  covered 
externally  with  a  wire  screen;  Z>,  valve  which  controls  this  opening; 
./?,  radiator;  R  B  tin-lined  box  surrounding  radiator;  T,  door  in  front  of 
box  which,  when  raised,  permits  the  air  in  the  room  to  circulate 
through  the  radiator  as  shown  by  the  arrows  X  X\yt  the  filtering 
screen  composed  of  cheese  cloth  held  in  place  by  wire  gratings. 


FIG.  32. 

In  public  buildings  attempts  are  sometimes  made  to  accomplish 
this  filtration,  as  well  as  to  secure  moisture  and  coolness,  by  passing 
the  air  through  sprays  or  thin  sheets  of  water.  Where  it  is  desirable 
to  filter  the  air  for  a  single  room,  as,  for  instance,  in  a  case  of  sickness, 
this  can  be  done  by  placing  a  large  frame  before  the  register,  covered 
with  two  or  three  layers  of  coarse  cotton  cloth.  Slices  of  coarse 
sponge  have  also  been  recommended  for  this  purpose,  but  they  ob- 
struct the  air  too  much.  If  the  sponge  be  moistened  and  hung  in 
front  of  the  register  it  will  act  to  some  extent  as  a  filter,  but  mainly  as 
a  source  of  moisture  to  the  air,  and  as  a  means  of  lowering  its  temper- 
ature by  the  rapid  evaporation  produced. 

In  living  rooms,  heated  by  a  hot-air  furnace  or  by  indirect  radia- 
tion by  steam,  the  use  of  a  large,  coarse,  moist  sponge  in  front  of  the 
register  will  often  be  a  source  of  great  comfort.  Vessels  of  porous 
clay,  through  which  water  percolates  rapidly,  are  used  for  the  same 
purpose. 

In  the  Glasgow  Infirmary  the  air  is  filtered  and  washed  by  being 
passed  through  a  screen  16  feet  long  and  12  feet  high,  formed  of 


250  FILTRATION    OF    AIR. 

cords  of  horse  hair  and  hemp  closely  wound  over  top  and  bottom 
rails,  which  screen  is  kept  constantly  moist  by  trickling  water  so  that 
dust  and  soot  particles  which  have  adhered  to  it  cannot  be  removed 
by  air  currents.  By  means  of  an  automatic  flush  tank  20  gallons  of 
water  are  discharged  over  the  surface  of  the  screen  every  hour  to 
wash  off  the  accumulated  particles.  By  means  of  aspirating  fans  the 
air  is  drawn  through  this  screen  at  the  rate  of  about  1,000  cubic  feet 
per  hour  for  each  square  foot  of  surface,  and  it  is  said  to  effectually  re- 
move all  soot  and  fog. 

The  advantage  of  dry  filtration  of  incoming  air  is  that  it  causes 
much  less  obstruction  to  the  current  than  a  wet  screen,  and  conse- 
quently requires  less  area.  The  disadvantage  is  that  it  must  be  fre- 
quently changed — while  by  the  use  of  a  spray  screen  or  a  wet  screen 
flushed  at  intervals,  the  dust  particles  are  washed  away.  The  objec- 
tion sometimes  urged  against  dry  screens  that  they  collect  germs 
which  may  afterwards  be  given  off  to  the  air  currents  is  of  small  im- 
portance, for  the  number  of  pathogenic  micro-organisms  in  the  free 
air  is  very  small,  and  so  far  as  these  are  concerned  it  is  not  worth 
while  to  attempt  to  free  the  external  air  from  them;  the  chief  use  of 
the  filter  screen  is  to  remove  particles  of  soot,  pulverized  straw,  horse 
dung,  etc.,  which  make  up  the  greater  part  of  ordinary  street  dusts. 

The  fact  that  at  a  certain  moderate  depth  the  temperature  of  the 
earth  is  found  to  be  uniform  at  all  seasons  has  long  been  known,  and  a 
number  of  proposals  have  been  made  to  utilize  this  in  heating  and 
ventilation.  In  his  work  on  the  British  Army  in  India,  published  in 
1858,  Dr.  Jeffreys  mentions  an  attempt  made  in  1824  to  ventilate  with 
cool  air  a  large  hospital  at  Cawnpore,  India,  by  means  of  a  long  and 
large  tunnel,  which,  he  says,  failed  because  the  cooling  surface  and  the 
depth  were  insufficient. 

In  another  part  of  the  same  work  he  proposes  to  ventilate  the 
soldiers'  barracks  in  India  by  making  use  of  this  principle,  saying  that 
u  we  may  view  the  uppermost  50  feet  of  the  earth's  surface — or  as 
many  feet  down  as  we  can  reach  without  the  intrusion  of  water — as 
one  vast  equalizing  reservoir,  ready  to  absorb,  from  any  amount  of  air 
we  may  choose  to  Subject  to  its  action,  a  large  proportion  of  its  sum- 
mer heat,  even  if  we  do  not  aid  our  reservoir  in  its  annual  emptying 
itself  of  such  heat  in  the  cold  season,  but  leave  it  to  conduct  back, 
spontaneously,  such  heat  tardily  upward  to  the  surface  during  the 
winter  months.  But  if  we  adopt  proper  measures  for  cooling  thor- 
oughly in  the  winter  the  mass  of  earth  we  select  for  our  absorbing 
reservoir,  we  may  have  it  emptied  of  more  than  the  accumulated  sum- 


EARTH    HEATING    AND    COOLING. 


251 


mer  heat  before  the  ensuing  hot  season,  and  brought  down  nearly  to 
the  winter  mean,  and  ready,  therefore,  to  absorb  again  much  more  heat 
than  when  it  had  to  cool  itself  by  the  tardy  spontaneous  process  of  up- 
ward conduction  through  its  whole  mass. 

"  Now,  if  we  select  contiguous  to  a  barrack  of  the  largest  size  a 
plot  of  ground,  A,  B,  C,  Z>,  Fig.  33,  only  100  yards  square,  or  120 
yards  long  by  80  yards  wide — less  might  do — and  prick  it  over  with 
wells  about  7  yards  apart,  the  cost  of  digging  them  all  will  be  only 
^20,  and  we  shall  possess  200  to  operate  upon  a  cubic  block  of  earth 
100  yards  square*  and,  say,  50  feet  deep.  There  are  numerous  parts 
of  India  in  which,  the  water  being  40  or  50  feet  or  more  from  the  sur- 
face, dry  wells  to  that  depth  may  be  dug;  but,  on  the  other  hand,  in 
many  localities,  as  at  Meerut,  Bareilly  and  Delhi,  the  depth  is  much 
less,  in  some  not  half  as  much.  In  such  places  the  number  of  the  wells 


FIG.  33- 

would  have  to  be  multiplied,  and  evaporation  from  the  water's  surface 
and  the  humid  sides  of  the  wells  would  make  up  for  the  effect  of  their 
inferior  depth.  Upon  the  plan  proving  effective  it  might  form 
an  important  object  in  the  choice  of  a  station,  to  select  localities  in 
which  the  refrigerator-well  ventilation  could  be  given  the  best  effect 

whether  with  deep  wells  and  a  drier  air,  or  with  shallow  and  more 

humid. 

"  At  Futtehgurh,  Cawnpore,  Agra,  and  in  Bundelcund,  etc.,  dry 
wells  from  40  to  70  feet  deep  may  be  dug. 

"  To  put  the  wells  in  action  we  may  proceed  thus  :  Let  £,  F,  G, 
etc.,  be  successive  rows  of  wells  ;  the  first  of  each  row,  JS  i,  F  i,  G  i, 
being  sunk  in  the  lower  veranda  of  the  barrack  throughout  its  length, 

*  The  plot  of  ground  may,  preferably,  be  oblong,  as  200  yards  by  50,  ac- 
cording to  the  length  of  the  barrack  or  barracks. 


252  EARTH    HEATING    AND    COOLING. 

though  this  is  not  necessary,  and  the  mouths  of  this  row  being  covered 
with  wooden  or  bamboo  gratings  to  guard  against  accidents. 

"All  the  wells  exterior  to  the  building,  excepting  the  furthermost 
of  each  row,  E  10,  F  10,  etc.,  must  have  their  mouths  closed  and 
plugged  for  some  feet  down,  by  straw  resting  on  a  simple  bamboo  frame 
propped  across  the  well,  as  at  O,  O,  <9,  etc. 

"  If  the  ground  is  wanted  for  exercising  the  men,  the  mouths  of  the 
wells  must  be  arched  over  with  brickwork  and  covered  level  with  the 
ground  around  ;  but  as  this  would  be  expensive,  and  the  ground  on  one 
side  of  a  barrack  can  generally  be  spared  to  that  moderate  extent,  the 
simplest  course  would  be  to  raise  a  common  mud  wall  a  foot  or  two 
high  round  each  well,  and  to  cover  the  straw,  plugging  its  mouth  with 
matting  or  a  thin  thatch.  The  earth  dug  from  the  wells  would  raise 
the  level  of  the  surface  about  a  foot,  and  would  in  general  yield,  if  the 
lower  sand  were  not  put  uppermost,  a  fertile  virgin  soil. 

"  The  whole  area  between  the  wells  might  form  a  productive  gar- 
den, with  its  surface  kept  cool  by  frequent  watering  from  a  few  wells  re- 
served and  deepened  for  the  purpose,  and  by  being  covered  with  vegeta- 
tion ;  but  it  must  not  be  such  vegetation  as  could  be  a  source  of 
malaria.  This  use  of  the  surface  would  appreciably  check  the  travel- 
ing of  heat  downward  into  our  cubic  reservoir  below. 

"  The  wells  of  each  row  must  be  made  to  communicate  with 
each  other,  thus  :  from  the  bottom  of  E  i,  a  horizontal  passage  P, 
about  2  */s  feet  high  and  15  or  18  inches  wide,  must  be  cut  to  the  bot- 
tom of  the  next  well  of  the  row  E  2,  and  from  near  the  top  of  this 
well  below  the  straw  about  10  feet,  beneath  the  surface  of  the  earth,  a 
similar  horizontal  passage  must  proceed  to  the  next  well  E  $,  and 
from  the  bottom  of  this  well  a  passage  to  E  4,  and  so  on  to  the  last 
well  E  10,  according  to  the  number  of  wells  in  the  row. 

"  This  last  well  being  surmounted  by  a  large  cowl  S  (turned  to  the 
wind  by  a  fan-tail  or  a  lever  moved  by  hand),  and  acting  as  a  wind-sail, 
the  wind  will  blow  down  it  and  through  the  passage  at  the  bottom  to 
the  next  well,  then  up  it  and  through  its  upper  passage  to  the  third 
well,  and  pursuing  this  course  through  all  the  wells,  will  make  its  exit 
through  the  grating  of  the  well  E  i,  and  into  the  veranda  T,  which 
should  be  securely  closed  As  in  each  row  of  wells  the  last  would  be 
similarly  surmounted  with  a  cowl,  every  first  well  of  each  row  would 
pour  forth  air  into  the  veranda." 

I  have  given  Dr.  Jeffreys'  description  in  full,  because  his  book  is 
somewat  rare,  and  because  the  principle  which  he  set  forth  has  been 
made  the  subject  of  one  or  two  comparatively  recent  patents,  as 


SUB-EARTH    VENTILATION.  253 

for  instance,  in  that  granted  to  Mr.  John  Wilkinson,  July  29,  1879, 
for  an  improvement  in  tempering  and  purifying  air  and  ventilating 
structures. 

In  1876  Mr.  Wilkinson  published  a  pamphlet  entitled,  "How  to 
construct  a  perfect  dairy-room,"  etc.,  in  which  he  gives  plans  for  a 
dairy  connected  with  a  subterraneous  duct  about  200  feet  long,  through 
which  the  air  supply  is  to  be  drawn,  and  since  that  time  he  has  written 
a  good  deal  for  the  daily  press  upon  the  merits  of  his  patent  sub-earth 
ventilation. 

March  n,  1879,  a  patent  was  granted  to  Morrill  A.  Shepard  for  an 
improvement  in  producing  heat  and  ventilation  by  sinking  wells  or 
shafts  to  reach  a  water-bearing  stratum,  in  which  are  to  be  laid  pipes 
through  which  the  air  supply  for  the  building  is  to  be  drawn.  As  Mr. 
Shepard's  object  is  to  have  his  fresh-air  supply  pipes  surrounded  by 
water  of  nearly  constant  temperature,  he  would  also  have  such  pipes 
laid  in  rivers  to  supply  adjacent  cities. 

The  principle  of  sub-earth  or  water  ventilation  having  been  dis- 
tinctly announced  by  Dr.  Jeffreys  in  1858,  anyone  is  at  liberty  to  make 
use  of  it,  but  it  is  only  under  special  circumstances  that  it  possesses 
any  practical  value.  In  cities  it  would  be  highly  inadvisable  to  use 
subterannean  passages  as  air-supply  sources,  because  of  the  great  risk 
of  contamination  of  the  air  with  deleterious  or  offensive  gases.  In  the 
country  there  is  less  risk  of  this,  but  even  there  the  percentage  of  car- 
bonic acid  in  the  air  will  be  markedly  increased  by  passing  it  through 
a  sub-earth  duct.  This,  however,  will  not  injure  it  for  dairy  supply, 
and  dairies  constructed  in  accordance  with  this  principle  will  be  found 
very  satisfactory  as  regards  ventilation  and  temperature. 

The  force  necessary  to  secure  a  movement  of  air  for  ventilating 
purposes  can,  of  course,  be  obtained  by  the  cooling  of  a  column  of  air 
in  a  shaft  as  certainly  as  by  heating  it,  the  essential  point  being  to 
produce  a  difference  in  the  weight  of  equal  volumes  of  air  by  giving  them 
different  temperatures,  and  then  utilizing  this  difference  in  weight  to 
produce  a  movement  of  air  in  the  direction  desired. 

In  the  great  majority  of  cases,  however,  it  will  be  found  much 
cheaper  and  simpler  to  do  this  by  adding  than  it  will  by  abstracting  heat. 

In  the  chapter  on  heating,  attention  has  been  called  to  the  desira- 
bility, in  arranging  the  heating  and  ventilation  of  a  large  building,  of 
preparing  schedules  of  the  different  rooms,  showing  for  each  the 
length,  breadth  and  height,  cubic  capacity,  area  of  windows  and  of  ex- 
ternal walls,  exposure  or  frontage,  purpose  or  use,  number  of  occu- 
pants, amount  of  air  supply,  and  amount  of  heating  surface. 


254  FRESH-AIR    INLETS. 

In  order  to  do  this  methodically,  the  rooms  on  each  floor  should 
be  numbered  in  regular  order,  and  then  scheduled,  the  floor  being 
designated  by  letters  of  the  alphabet.  B  7,  then,  indicates  room  No.  7 
on  the  second  floor,  and  this  mark  can  be  placed  on  the  plans  on  all 
flues  connected  with  this  room. 

Having  these  data  and  the  floor  plans  before  us,  the  next  step  is 
to  locate  on  the  plans  the  position  of  inlets,  outlets  and  flues,  and  to 
indicate  their  sizes.  The  area  of  the  fresh-air  registers  or  inlets  will 
depend  somewhat  upon  the  location  in  the  room  at  which  the  air  is  to 
be  introduced,  and  this  location  must  be  determined  by  the  following 
considerations  : 

First. — The  register  must  be  in  such  a  position  and  of  such  size 
that  the  requisite  amount  of  air  can  be  introduced  through  it  without 
causing  currents  of  air  of  such  velocity  as  will  cause  discomfort  to  the 
occupants  of  the  room.  The  only  difficulty  in  this  respect  occurs  in 
rooms  occupied  by  a  number  of  persons,  such  as  assembly  and  school- 
rooms, churches,  theaters,  hospitals,  etc.  Under  such  circumstances  it 
is  sometimes  difficult  to  so  locate  the  fresh-air  inlets  that  the  currents 
therefrom  will  not  be  unpleasantly  perceptible  if  they  are  rapid,  and  it 
may  then  become  necessary  to  make  these  inlets  of  such  an  area  that 
the  velocity  of  the  inflowing  air  need  not  exceed  i^  feet  per  second  to 
secure  the  introduction  of  an  amount  sufficient  for  both  warming  and 
ventilation.  Bearing  in  mind  the  tendency  of  air  to  adhere  to 
surfaces,  it  will  almost  always  be  possible,  by  the  use  of  deflecting 
or  baffling  plates  or  screens,  to  direct  the  incoming  current  in 
such  a  manner  that  it  will  not  cause  draughts.  In  churches, 
theaters  and  assembly  halls  the  fresh-air  inlets  should  be  so  placed  as 
to  avoid  interference  with  the  acoustic  properties  of  the  room,  as  will  be 
explained  in  the  chapters  treating  of  the  ventilation  of  such  buildings. 
When  the  registers  are  so  situated  that  the  currents  from  them  will 
produce  no  discomfort  they  may  be  made  smaller,  provided  that  suffi- 
cient power  is  applied  to  make  the  current  swifter.  For  example,  if  it  be 
determined  to  introduce  the  fresh  air  directly  through  a  perforated 
floor  in  an  assembly  room,  the  total  area  of  openings  should  be  at  least 
100  square  inches  for  each  occupant,  while  the  area  of  register  open- 
ings need  not  be  more  than  30  square  inches  for  each  occupant  if  they 
are  placed  near  the  ceiling,  and  a  fan  is  used  to  ensure  the  requisite 
velocity. 

Second. — Taking  it  for  granted  that  the  fresh  air  is  to  be  warmed 
in  cold  weather  before  it  is  brought  into  the  room,  its  registers  must  not 
be  placed  below  the  foul-air  registers,  unless  the  former  are  scattered 


INLETS    AND    OUTLETS.  255 

all  over  the  floor  of  the  room.  The  reason  for  this  is,  that  direct  cur- 
rents between  the  inflow  and  outflow  registers  are  easily  established 
when  the  latter  are  above  the  former,  and  in  such  case  little  change  is 
effected  in  the  great  mass  of  the  air  in  the  room. 

Third. — Flues  of  proper  size  cannot  usually  be  placed  in  thin 
walls,  such  as  ordinary  interior  partitions.  A  flue  measuring  less  than 
5  inches  in  its  smallest  diameter  is  of  little  use.  Fortunately,  in  ordinary 
dwelling  houses,  where  this  difficulty  of  thin  partition  walls  is  greatest, 
the  precise  location  of  fresh  and  foul-air  flues  is  of  minor  importance 
so  long  as  the  precaution  advised  in  the  preceding  section  be  observed. 

Fourth. — Fresh-air  registers  should  not  be  placed  in  a  floor  so  as 
to  be  flush  with  its  surface,  because  dust  and  dirt  will  fall  into  the  flues 
and  be  returned  to  a  certain  extent  in  the  column  of  ascending  air. 
Such  registers  are  also  a  fruitful  source  of  loss  of  small  articles.  It  is 
always  possible  to  continue  the  flue  upward  into  a  step  or  seat,  and  then 
place  the  register  in  the  side  of  this. 

There  is  less  objection  to  placing  foul-air  registers  in  the  floor; 
but  even  this  should  be  avoided  unless  the  openings  are  covered  by 
some  article  of  furniture,  as  for  instance,  in  a  hospital  ward,  where  a 
good  position  for  the  foul-air  registers  is  in  the  floor  beneath  each  bed  ; 
and  even  then  the  register  should  not  be  flush  with  the  floor,  but  rise 
an  inch  or  two  above  its  surface. 

Fifth. — In  dwelling  houses  and  buildings  of  moderate  size  it  is 
economical  to  centralize  the  heating  apparatus  as  much  as  possible, 
keeping  the  fresh-air  flues  in  inner  walls ;  but  it  is  not  easy  by  this 
method  to  secure  sufficient  warmth  in  the  vicinity  of  windows,  espe- 
cially on  the  side  most  exposed  to  the  winter  winds. 

On  the  other  hand,  hot-air  flues  should  not  be  placed  in  outer 
walls,  unless  these  are  thick  and  substantial,  and  even  then  it  will  be 
good  economy  to  make  the  flue  of  terra-cotta  or  galvanized  iron,  so  set 
as  to  leave  an  air  space  of  an  inch  or  two  on  the  outer  side.  For 
rooms  on  the  floor  immediately  above  the  radiators,  it  is  not  necessary 
to  place  flues  in  the  walls  in  order  to  bring  the  registers  under  or  near 
the  windows,  which  is  their  best  place  so  far  as  heating  is  concerned. 
Foul-air  flues  should  not  be  placed  in  outer  walls,  unless  they  are  to 
be  carried  downward  and  to  have  some  means  of  aspiration  connected 
with  them. 

Sixth. — General  Morin,  and  the  majority  of  modern  French  engi. 
neers,  advise  that  the  place  of  introduction  of  fresh  air  shall  be  near 
the  ceiling,  in  order  to  avoid  unpleasant  currents,  while  the  discharge 
openings,  on  the  contrary,  should  be  near  the  floor.  The  introduction 


2^6  INLETS    AND    OUTLETS. 

of  warm  air  near  the  ceiling,  in  order  to  prevent  disagreeable  currents, 
is  not  absolutely  essential,  for  such  currents  can  be  avoided,  as  above 
explained,  by  making  the  registers  of  proper  size;  and  to  secure  com- 
fort in  cold  weather,  it  is  necessary,  on  this  plan,  that  the  air  shall  be 
introduced  at  a  temperature  several  degrees  higher  than  is  required  if 
it  be  admitted  at  a  lower  level. 

The  proper  position  of  the  foul-air  registers  depends  on  the  pur- 
pose of  the  room  and  on  the  season.  During  cold  weather,  in  the 
majority  of  cases  they  should  be  near  the  level  of  the  floor,  to  secure 
a  satisfactory  distribution  of  the  air  with  the  least  expense.  In  large 
assembly  halls,  however,  and  especially  where  it  is  desired  to  provide 
for  respiration-air  as  pure  as  possible  instead  of  foul  air  diluted  to  a 
certain  standard,  the  discharge  openings  should  be  above. 

Seventh. — In  order  to  secure  a  thorough  distribution  of  the  in- 
coming air,  it  is  usually  recommended  that  the  discharge  openings 
should  be  in  the  side  of  the  room  opposite  to  that  in  which  the  fresh- 
air  openings  are  placed,  and  as  far  as  possible  from  them. 

In  all  dwelling  houses,  however,  and  in  rooms  not  having  win- 
dows on  opposite  sides  nor  containing  a  sufficient  number  of  occu- 
pants to  exercise  any  special  influence  on  the  temperature,  good  ven- 
tilation will  be  secured  by  placing  the  fresh  warm-air  openings  on  an 
inner  wall,  and  the  discharge  openings  in  the  same  wall  at  the  same  or 
a  lower  level.  This  is  the  arrangement  in  most  dwellings  heated  by 
indirect  radiation,  the  fresh-air  register  being  in  the  side  of  the  chim- 
ney near  the  floor,  and  the  foul  air  passing  out  through  perforated  fire- 
boards  on  the  same  level  a  few  feet  away.  The  result  is  the  establish- 
ment of  a  circulation  from  the  fresh-air  opening  upward  and  along  the 
ceiling  to  the  outer  walls  and  windows,  thence  down  the  wall  to  the 
floor,  and  along  the  floor  to  the  discharge. 

But  when  we  come  to  deal  with  rooms  having  a  large  floor-area  in 
proportion  to  the  height,  and  containing  50  or  more  persons,  whose 
heat  production  is  a  factor  that  must  betaken  into  consideration,  there 
is  some  danger  in  this  method  that  there  will  be  an  unsatisfactory  dis- 
tribution of  the  fresh  air  when  the  temperature  of  the  external  air  is 
not  below  50°  F. 

It  has,  however,  been  applied  to  school  rooms  with  reported  good 
success,  and  the  reader  is  referred  to  the  chapter  on  school  houses  for 
details. 

Eighth. — Each  room  should  have  its  own  fresh  or  warm-air  flue 
separate  from  all  others.  Two  or  more  rooms  above  each  other  should 
never  be  supplied  from  one  common  flue. 


FRESH-AIR    INLETS.  257 

The  area  of  the  inlet  register  should  have  a  clear  area  of  opening, 
exclusive  of  the  iron  grating  work,  from  20  to  25  per  cent,  larger  than 
that  of  the  flue  which  supplies  it,  if  this  flue  be  a  small  one.  This  is 
because  of  the  considerable  obstruction  to  the  air  current  produced  by 
the  valves  and  the  ornamental  work  in  front  of  the  register  which  not 
only  diminish  its  effective  area  of  opening  but  produce  much  friction. 
The  size  to  be  given  to  inlet  and  outlet  flues  depends  on  the  quantity 
of  air  to  be  passed  through  them  and  the  velocity  permissible  or  ob- 
tainable. In  estimating  this  velocity  much  depends  upon  whether  the 
current  is  to  be  produced  by  differences  of  temperature  only  or  by 
mechanical  power  as  by  a  fan,  but  even  when  a  fan  is  used  the  velocity 
should  not  be  over  10  feet  per  second  in  the  smaller  flues  or  there  will 
be  great  waste  of  power  from  friction.  In  inlet  flues  coming  from  the 
basement  in  case  of  heating  by  indirect  radiation  the  velocity  will  in- 
crease with  the  length  of  the  flue,  other  things  being  equal.  In  the 
flues  leading  to  the  first  floor  the  velocity  will  usually  not  exceed  4 
feet  per  second,  while  in  those  to  the  second  floor  5  feet  per  second, 


FIG.  34. 

and  to  the  third  floor  from  6  to  7  feet  per  second  may  be  counted  on 
when  the  external  temperature  is  below  50°  F.  For  the  same  reason 
the  velocity  in  upcast  foul-air  flues  is  greater  in  those  of  the  lower 
stories  than  it  is  in  those  of  the  upper. 

With  regard  to  inlets  for  fresh  air  to  come  in  directly  from  with- 
out and  not  to  pass  through  or  over  any  heating  apparatus,  there  are  a 
variety  of  contrivances  intended  to  give  such  a  direction  to  the  enter- 
ing current  that  it  shall  become  diffused  and  imperceptible  by  the  time 
the  air  reaches  the  persons  in  the  room  and  usually  this  is  effected  by 
giving  the  current  an  upward  direction.  As  an  example  of  this  kind  of 
inlet  we  may  take  the  Sheringham  valve  which  is  much  used  in 
English  barracks,  but  which  in  this  country  is  chiefly  employed  in 
stables. 

In  this  the  air  enters  through  perforated  bricks  or  an  opening 
covered  with  wire  gauze  or  perforated  zinc,  and  is  then  directed  up- 
ward by  a  valve  opening,  the  deflecting  plate  of  which  is  so  arranged 


258  TOBIN'S  FLUES. 

that  it  can  be  set  at  any  angle  or  made  to  close  the  opening  entirely. 
(Fig.  34.)  The  internal  opening  of  these  valves  usually  measures  gffx^ff. 

If  the  room  is  heated  by  indirect  radiation  such  valves  would  in 
most  cases  become  outlets.  They  are  most  useful  in  moderate  weather 
and  in  rooms  heated  by  direct  radiation. 

Another  form  of  direct  cold-air  inlet  consists  of  tubes  entering  the 
room  at  any  convenient  point  above  the  floor  level  and  then  bent  up- 
wards so  as  to  produce  a  vertical  current  like  the  jet  of  a  fountain  to 
which  the  ceiling  of  a  room  of  ordinary  height  will  act  as  a  deflecting 
plate. 

For  dining  rooms,  smoking  rooms,  and  reception  and  drawing 
rooms  in  dwelling  houses,  where  it  is  desirable  to  make  provision  for 
the  gathering  of  a  considerable  number  of  persons  with  extra  lights,  on 
special  occasions,  while  usually  there  will  be  comparatively  few  per- 
sons with  ordinary  illumination,  a  modification  of  this  vertical-tube 
system  will  give  good  results  when  the  external  temperature  is  not  too 
low.  These  air  ducts  may  be  made  of  zinc  or  galvanized  iron,  and  be 
brought  up  in  the  jambs  of  the  fireplace.  If  there  be  a  high  mantel, 
the  openings  of  the  tube  may  be  on  a  level  with  the  mantel  and  cov- 
ered with  a  wire  grating,  which  maybe  double  to  permit  of  the  insertion 
of  cheese  cloth  or  a  thin  layer  of  cotton  batting  to  serve  as  a  filter.  If 
the  mantel  be  a  low  one,  the  tubes  may  be  carried  up  to  a  height  of 
from  6  to  8  feet  above  the  floor,  and  open  through  a  bracket  or 
pedestal.  These  tubes  may  be  about  4//x6//,  opening  to  the  ex- 
ternal air  through  perforated  terra-cotta  panels,  or  by  openings  covered 
with  wire  netting  painted  the  same  color  as  the  surrounding  wall,  and 
should  have  dampers  or  butterfly  valves,  which  can  be  worked  from 
within  the  room.  The  external  opening  may  be  at  any  convenient 
height  to  suit  the  exterior  appearance,  but  the  vertical  portion  of  the 
tube  should  not  be  less  than  3  feet  in  length. 

Such  tubes  are  commonly  known  as  Tobin's  tubes.  They  are 
liable  to  become  receptacles  for  dust,  dead  insects,  etc.,  and  to  become 
obstructed  by  cobwebs,  so  that  they  require  attention  as  to  internal  as 
well  as  external  cleanliness.  Mr.  Tobin  supposed  that  if  these  tubes 
were  used  there  would  be  no  need  for  special  outlets,  but  this  is  an  error 
— they  work  well  only  where  there  is  an  outlet  flue  properly  arranged. 

In  some  cases  the  air  may  be  brought  in  and  distributed  by  per- 
forated cornices,  with  good  effect.  In  all  cases  in  which  the  air  is 
introduced  through  many  small  openings,  it  is  well  to  have  these  open- 
ings trumpet-shaped,  flaring  inward  to  facilitate  the  rapid  diffusion  of 
the  current,  and  the  ordinary  cast-iron  wall  registers  could  easily  be 


WINDOW    INLETS. 


259 


much  improved  in  this  way  by  making  the  bars  triangular  with  the 
apex  towards  the  room. 

There  are  many  forms  of  window  inlets,  the  simplest,  next  to 
opening  the  window  itself,  being  formed  by  raising  the  lower  sash  about 
6  inches,  and  placing  a  piece  of  board  so  as  to  fill  the  space  thus  left 
between  the  bottom  of  the  sash  and  the  sill.  There  is  thus  formed  an 
opening  between  the  lower  and  upper  sashes  through  which  the  incom- 
ing air  streams  upward.  This  may  be  supplemented  by  having  the 
board  perforated  with  one  or  more  4-inch  tubes  bent  upward  on  the 
inside,  and  having  within  them  a  damper,  or  butterfly  valve  to  control 
the  current. 


FIG.  35. 

Another  form  of  window  ventilator,  suggested  by  Dr.  Rosebrugh,* 
consists  of  a  short  supplemental  sash  placed  outside  of  the  window  at  the 
top,  close  against  the  top  part  of  the  upper  sash.  When  the  top  sash  is 
lowered,  this  extra  sash  prevents  a  direct  draught  from  the  top  of  the 
window  while  the  air  enters  in  the  space  between  the  upper  and  lower 
sash. 

Still  another  simple  form  of  window  ventilator  which  is  said  to 
work  very  satisfactorily,  is  shown  in  Figs.  35  and  36,  taken  from  The 

*  Canadian  Practitioner,  XVII.,  1892,  p.  103. 


260 


WINDOW    INLETS. 


Engineering  Record  for  June  13,  1891.  The  side  strips  securing  the 
lower  sash  are  omitted  on  one  side,  and  on  the  other  they  are  made  in 
two  pieces  A  A,  pivoted  top  and  bottom  and  united  in  the  middle  by 
a  slotted  hinge  B,  thus  permitting  the  lower  sash  to  tip  inwards  and 
leave  an  open  space  at  its  top,  while  the  bottom  remains  close  against 
the  window  seat. 


FIG.  36. 

The  upper  part  of  Fig.  36  is  an  elevation  when  the  sash  is  closed, 
the  lower  part  is  a  section  at  Z  Z.  C  is  a  hook  securing  the  sashes  in 
a  closed  position.  D  is  a  graduated  bar  to  regulate  the  amount  of 
opening,  and  E  is  the  latch. 

In  connection  with  systems  of  air-heating  by  indirect  radiation,  it 
is  very  desirable  to  provide  means  by  which  it  shall  be  possible  to 


BY-PASSES. 


26l 


quickly  control  and  vary  within  certain  limits  the  temperature  in  a 
given  room,  without  interfering  with  the  fresh-air  supply. 

In  the  majority  of  cases  this  can  be  best  effected  by  providing 
switch  valves  in  connection  with  the  fresh-air  ducts  and  radiators,  so 
arranged  that  by  turning  or  pulling  a  handle  placed  in  the  room  to  be 
warmed,  an  inmate  of  that  room  can  compel  the  fresh  incoming  air  to 
either  pass  wholly  through  the  box  or  case  containing  the  radiators, 
or  wholly  outside  of  it,  or  partly  through  and  partly  around  it,  so  as  to 
produce  by  mixture  any  temperature  desired. 

Many  different  ways  of  arranging  such  a  switch  valve  can  readily 
be  devised.  The  following  are  illustrations  of  various  forms,  which 


PIG.  37- 

will  be  found  suggestive  and  which  are  for  the  most  part  self  explan- 
atory: 

Figure  37  shows  a  simple  and  cheap  form  of  such  a  valve,  pro- 
posed by  Messrs.  Gillis  &  Geoghegan,  of  New  York  City. 

Figure  38  is  a  form  used  by  Baker,  Smith  &  Co. 

Figure  39  shows  a  more  satisfactory,  but  more  expensive  pattern, 
proposed  by  Mr.  C.  W.  Newton. 

Figure  40  shows  the  switch-valve  arrangement  employed  in  the 
Johns  Hopkins  Hospital,  in  Baltimore,  in  connection  with  the  hot- 
water  coils  placed  beneath  the  wards. 

Figure  41  is  the  section  of  a  form  of  radiator  and  switch  valve 
recommended  for  hospital  use  by  Dr.  Norton  Folsom,  of  Boston. 


262 


BY-PASSES. 


>§ 


FIG.  38.-SWITCH  VALVE  FOR  HEATING  COILS. 


BY-PASSES. 


263 


FlG.  39—NEWTON'S  SWITCH  VALVE  FOR   STEAM-HEATING  COILS. 


264 


BY-PASSES. 


SWITCH 

HOPKINS 

COMMON 


ELEVATION 


SECTION 


FIG.  40— HEATING  COILS  AND  SWITCH  VALVES. -JOHNS  HOPKINS  HOSPITAL. 


BY-PASSES. 


265 


FIG.  41.— SWITCH  VALVE  RECOMMENDED  BY  DR.  N.  FOLSOM. 


266 


BY-PASSES. 


The  "switch"  or  "mixing  valve"  shown  in  Fig.  42  was  de- 
signed by  Mr.  A.  Mercer,  of  New  York,  for  the  Bridgeport  Hospital. 

The  casings  of  the  radiators  are  metal,  with  a  by-pass  at  a.  The 
valve  consists  essentially  of  the  damper  a,  rod  and  crank  b,  lever  c,  and 
pull  dy  with  the  set  or  thumb  screw  e.  The  rod  at  d'  may  be  marked 


FIG.  42. -DETAIL  OF  MIXING  VALVE. 


to  degrees  or  fractional  parts  of  the  opening,  and  in  other  respects  the 
sketch  shows  for  itself. 

Figure  43  illustrates  another  form  of  "switch  valve,"  in  which  all 
the  movable  parts  are  in  the  register.  It  was  designed  by  Mr.  William 
J.  Baldwin,  of  New  York,  for  the  Moses  Taylor  Hospital,  at  Scranton, 
Pa. 


BY-PASSES. 


267 


The  hospital  is  on  the  pavilion  plan,  the  wards  being  a  single 
story.  The  air  from  a  blowing  fan  enters  the  basements  under  the 
wards,  where  it  is  to  be  warmed  to  about  60  degrees,  by  being  passed 
through  a  large  coil,  which  utilizes  the  exhaust  steam  from  the  engine 
which  drives  the  fan.  This  converts  the  basements  into  a  plenum,  from 
which  the  air  can  be  passed  to  supplementary  steam  coils  on  its  way  to 


FIG.   43-  —PLAN  AND  SECTION  OF  MIXING  REGISTER. 

the  wards,  and  be  made  warmer,  or  it  may  be  passed  direct  into  the 
wards,  or  any  mixture  of  the  air  at  the  two  temperatures  may  be  passed 
in,  but  by  no  means  can  the  air  supply  be  reduced.  It  is  a  circular 
register  to  all  outward  appearance,  and  is  connected  with  a  sheet-iron 
tube,  which  goes  through  the  floor.  This  tube  is  divided  its  whole 
length  by  a  septum,  so  as  to  form  two  semi-circular  tubes.  One  of 


268 


BY-PASSES. 


these  halves  is  connected  to  the  supplementary-coil  chamber,  and  has 
a  stopper  at  the  bottom,  while  the  other  half  is  open.  The  register, 
instead  of  having  valves  in  the  ordinary  way,  has  a  solid  semi-circular 
disk,  which  can  be  revolved  under  the  fretwork  by  a  key  introduced 
into  the  slot  in  the  middle,  as  shown.  This  semi-circular  disk  may  be 
turned  so  as  to  close  one  or  other  of  the  semi-circular  pipes,  or  it  may 
be  made  to  cover  one-half  of  each,  so  that  one-quarter  of  the  fretwork 
is  delivering  air  at  60  degrees,  while  another  quarter  is  delivering  air 
at  120  degrees,  or  any  other  proportions  of  the  two  currents  may  be 
obtained  by  shifting  the  position  of  the  semi-circular  disk  without  re- 
ducing the  volume. 

A  modification  of  this  register  for  side-wall  flues  has  also  been  de- 
signed by  the  same  person. 

The  method  used  in  the  Orthopaedic  Hospital,  in  New  York,  is 
shown  in  Figs.  44  and  45. 


FIG.  44. 

This  was  designed  by  Mr.  Baldwin,  who  gives  the  following  de- 
scription in  The  Engineering  Record  of  January  2,  1892  : 

Figure  44  shows  the  connection  in  the  basement  of  the  branch  from 
the  blast  main,  with  a  vertical  flue  K  (8*xi5*  or  20  inches),  in  the 
20-inch  brick  main  wall  W.  S  is  a  galvanized-iron  stack,  with  conduit 
C,  and  contains  an  indirect  steam  radiator  .#,  which  rests  on  heavy 
iron-pipe  bearers  P  P,  which  are  supported  by  hangers  If  H,  and 
clamps  to  the  iron  floor  beams  7  /.  The  damper  D  is  hinged  to  a 
solid  frame  £7,  so  that  the  outer  end  is  always  inside  the  blast  pipe. 
A  is  a  lever  arm  for  operating  Z>,  and  is  made  so  heavy  as  to  weight  it 
and  carry  it  down  positively  when  released.  B  is  a  safety  chain  con- 
necting A  with  the  lower  arm  E  of  bent  lever  7\at  the  foot  of  the  wall 
flue.  F  is  connected  by  chain  G  with  lever  L  (Fig.  45),  which  is  fixed 


BY-PASSES. 


269 


on  the  ^6-inch  square  shaft  M,  that  works  in  a  hole  drilled  in  the  wall 
just  above  the  register.  One  end  of  M  works  in  a  gas-pipe  thimble 
bearing  N,  and  the  other  is  turned  to  fit  a  hole  drilled  at  T,  in  the 
center  of  a  brass  sector  ./?,  to  which  it  is  secured  by  a  nut  6".  Tfye 


sector  jR  is  screwed  on  to  the  finished  interior  face  of  the  wall,  and  on 
it  works  the  hand  lever  O,  which  is  fixed  on  shaft  J/,  and  can  be  set  at 
any  part  of  the  arc  by  the  set  screw  Q  in  guide  bar  P.  The  operation 


270 


MIXING    VALVES. 


of  levers  and  dampers  is  evident.  The  air  may  be  mixed  to  the  desired 
proportion  of  hot  and  cold  by  setting  lever  O  at  any  of  the  inter- 
mediate positions  Z  Z,  etc.,  so  as  to  let  damper  D  occupy  a  corres- 
ponding intermediate  position  and  allow  part  of  the  air  to  enter  above 
and  part  below  the  radiator,  but  in  whatever  position  it  is  the  inlet  is 
never  closed  but  must  always  admit  a  full  quantity  of  air. 

The  levers  are  made  of  brass,  and  nickel-plated  where  exposed 
to  view.  Just  below  sector  S  is  hung  a  thermometer  on  the  face  of 
the  register,  and  it  is  found  possible  to  regulate  the  temperature  within 
3  degrees  of  any  required  point. 

Still, another  device  of  Mr.  Baldwin  for  the  same  purpose  is  shown 
in  Fig.  46.  This  is  used  in  the  building  of  the  College  of  Physicians 
and  Surgeons  in  which  both  heated  and  cool  air  are  brought  in  ducts, 
under  pressure  to  the  several  rooms. 


FIG.  46. 


The  twin  ducts,  supplying  warm  and  comparatively  cold  air,  are 
fitted  with  heads  K>  Fig.  i,  placed  in  the  various  rooms  of  the  build- 
ing and  set  into  the  walls.  The  warm  and  cold-air  pipes  /  and  J  open 
into  the  bottoms  of  these  heads  and  are  controlled  by  the  valve  Z, 
shown  also  in  Figs.  2  and  3.  The  warm  and  cold  air,  discharging  from 
the  ducts  /  and  /,  mixes  in  the  head  K,  and  enters  the  room  through 
the  side  opening.  The  valve  L  consists  of  a  slide,  guided  across  the 
duct  openings  by  the  guides  /  /,  and  operated  by  a  lever  M,  which  is 
pivoted  to  the  head  K.  The  slide  is  of  such  a  length  that  when  in  a 


BY-PASSES. 


271 


position  central  between  the  duct  openings  it  closes  one-half  of  each 
of  these.  Consequently  when  the  slide  is  moved  in  a  direction  to 
close  one  of  the  openings,  the  other  is  proportionately  opened  (Fig.  2). 
A  full  supply  of  fresh  air  is  thus  always  obtained. 

Figure  47  is  a  cross-section  of  a  form  of  by-pass  radiators  de- 
vised by  Dr.  A.  C.  Abbott  for  the  dog  hospital  of  the  department  of 
Veterinary  Medicine  of  the  University  of  Pennsylvania,  being  a  modi- 
fication of  that  used  in  the  Laboratory  of  Hygiene  previously  shown  in 
Fig.  3  2. 

A  wooden  box  lined  with  tin,  located  beneath  the  window  sill  S. 
The  box  is  divided  longitudinally  by  the  partition,  which  does  not 


FIG.  47. 


reach  to  the  floor,  but  allows  sufficient  space  for  passage  of  air  from 
the  air  inlet  /,  to  the  radiator  R.  The  box  can  be  closed  and  air 
supply  cut  off  by  the  swinging  cover  C  in  the  cut  hooked  back  against 
the  sill  of  the  window.  The  front  of  the  box  B  also  swings  out  on  a 
hinge,  thus  permitting  access  to  radiator. 

The  top  of  the  box  through  which  the  air  enters  the  room  is 
covered  by  cheese  cloth  dust  filters  which  rest  between  two  layers  of 
wire  netting,  x  represents  a  damper  fan  directing  the  air  entering  the 
room  either  through  the  section  y  of  the  radiator,  in  which  case  the  air 
is  not  warmed,  or  by  reversing  its  position  the  air  is  directed  over  the 
radiator  R  and  enters  the  room  as  warm  air.  The  two  extreme  positions 
of  the  damper  x  are  represented  by  the  intersecting  dotted  and  con- 


272  BY-PASSES. 

tinuous  lines.  By  placing  it  intermediate  between  these  extremes  part 
of  the  air  enters  the  room  without  passing"over  the  radiator  while  the 
remainder  is  warmed  by  passing  over  the  radiator. 

The  quadrant  to  the  right  of  the  cut  indicates  the  lever  to  be  placed 
on  the  outside  end  of  the  box  ;  when  the  lever  is  opposite  H  only  hot 
air  enters,  when  opposite  c  only  cold  air,  when  intermediate  between 
the  two,  air  of  medium  temperature  comes  in. 

It  is  very  desirable  that  some  form  of  valve  calculated  to  effect 
the  purpose  for  which  the  above  are  suggested  should  be  used  much 
more  extensively  than  is  at  present  the  case,  and  it  is  in  this  direction 
that  the  most  immediate  and  important  improvement  of  ventilation  of 
dwelling  houses  in  this  climate  can  be  effected. 

Nor  should  the  application  of  this  method  be  confined  to  steam 
and  hot-water  heating,  seeing  that  it  is  quite  as  important,  to  say  the 
least,  in  furnace-heated  houses.  At  present,  in  the  most  costly  dwell- 
ings heated  by  indirect  radiation,  the  only  way  to  promptly  diminish 
the  heat  when  it  becomes  oppressive  is  to  close  the  register,  and  shut 
out  the  fresh  air  as  well.  It  may  be  well,  however,  to  warn  the  archi- 
tect or  heating  engineer  that  to  obtain  good  results  from  this  device  it 
is  necessary  that  the  occupants  of  the  room  should  know  how  to  use  it, 
and  should  be  willing  to  do  so,  and  that  to  secure  this  willingness,  it  is 
desirable  to  obtain  their  co-operation.  Such  valves  were  provided  for 
the  radiators  supplying  the  private  parlors  in  a  large  club  house  in 
New  York,  and  the  louvers  or  dampers  were  removed  from  the  regis- 
ters to  prevent  persons  who  did  not  understand  the  apparatus  from 
shutting  off  the  air.  The  result  was  that  some  of  the  members  in- 
sisted on  having  the  louvers  replaced  in  order  that  they  might  be 
able  to  turn  them  as  they  had  been  accustomed  to  do.  A  little 
educational  work  would  not  have  been  wasted  in  this  instance. 


CHAPTER  XII. 

FOUL-AIR    OR    UPCAST    SHAFTS — COWLS,    SYPHONS. 

IN  the  preceding  chap'er  some  remarks  have  been  made  with  regard 
to  the  proper  position  for  foul-air  registers,  the  general  rule  being 
that  in  cold  weather,  in  all  rooms  except  legislative  halls  and  theaters, 
such  openings  should  be  near  the  level  of  the  floor,  to  draw  off  the  air 
which  has  been  cooled  by  windows  and  walls,  and  to  prevent  undue 
loss  of  heat.  This  forms  what  is  called  "downward  ventilation."  In 
moderate  weather  when  the  air  is  not  artificially  warmed,  it  is  prefer- 
able that  the  foul-air  registers  should  be  in  the  upper  part  of  the  room, 
and  they  may  open  into  the  flues  with  which  the  lower  openings,  for 
use  in  cold  weather,  are  connected.  So  far  as  the  production  of 
draughts  is  concerned,  there  is  no  objection  to  a  velocity  of  current  of 
6  or  8  feet  per  second  through  the  foul-air  outlets,  but  it  will  not 
do  to  assume  that  the  current  will  have  that  velocity  and  adjust  the 
size  accordingly.  If  what  is  called  natural  ventilation  is  to  be  relied 
on,  a  velocity  of  5  feet  per  second  in  lower  rooms,  and  of  4  feet 
per  second  in  upper  rooms  forms  the  safest  basis  for  calculation.  If 
aspiration  by  a  fan  or  heated  flue  is  employed  the  velocity  may  be 
assumed  to  be  6  feet  per  second. 

As  a  rule,  wall  registers  opening  into  foul-air  flues  are  unneces- 
sarily and  improperly  constructed  with  an  excess  of  ornamental  iron- 
work, louvers,  etc.,  which  greatly  obstruct  the  passage  of  the  air.  In 
large  rooms,  barracks,  school  rooms,  etc.,  it  is  better  to  omit  the  reg- 
ister and  put  in  its  place  a  solid  shutter  which  may  be  made  to  either 
slide  or  swing,  and  which  can  be  adjusted  so  as  to  leave  the  outlet 
entirely  open  or  entirely  closed. 

The  remarks  in  the  preceding  chapter  with  regard  to  calculating 
sizes  of  fresh-air  flues,  apply  also  to  foul-air  flues.  In  all  large  flues  of 
this  kind  the  average  velocity  may  be  assumed  to  be  6  feet  per  second. 
If,  for  example,  in  a  small  hospital  ward  the  amount  of  air  to  be  sup- 
plied and  removed  is  fixed  at  72,000  cubic  feet  per  hour,  or  20 
cubic  feet  per  second,  then  a  single  foul-air  shaft  for  such  a  ward 
should  have  an  area  of  about  3.^3  square  feet. 

In  arranging  the  ventilation  for  a  large  building  of  several  stories, 
the  architect  may  choose  between  several  different  systems  in  planning 


274  FOUL-AIR    FLUES. 

his  foul-air  or  upcast  shafts.  Suppose,  for  example,  that  the  building 
in  question  is  a  large  school  house  or  a  hotel,  or  a  building  containing 
a  large  number  of  offices. 

In  the  first  place,  he  may  give  a  separate  foul-air  shaft  to  every 
room,  which  shaft  shall  pass  directly  upward  to  the  outer  air  above  the 
roof.  The  simplest  way  to  do  this  is  to  give  a  fireplace  and  separate 
chimney  flue  to  each  room.  The  objections  to  this  are  the  increased 
cost,  the  difficulty  of  arranging  so  many  flues  and  chimneys  in  the 
walls  and  on  the  roof — increased  danger  from  fire,  and  the  risk  that 
one  flue  will  pull  against  another. 

In  buildings  of  such  size  and  importance  that  it  is  worth  while  to 
provide  some  form  of  centralized  heating  for  them  by  means  of  steam 
or  hot  water,  the  architect  will  usually  prefer  to  gather  the  majority  of 
the  foul-air  flues  into  a  few,  and,  if  possible,  one  large  upcast  shaft,  in 
•connection  with  which  he  can  provide  means  to  secure  a  constant  cur- 
rent, and  to  regulate  its  velocity  to  suit  the  varying  requirements  of  the 
season  or  of  the  inmates  of  the  building.  This  collection  of  the  flues 
into  a  central  shaft  may  be  effected  in  four  different  ways,  which  are 
well  discussed  and  illustrated  by  Planat.* 

The  first  of  these  is  what  Planat  calls  aspiration  from  above,  by 
which  he  does  not  mean  aspiration  from  the  upper  part  of  each  room, 
but  from  a  point  above  all  the  rooms — usually  in  the  attic — to  which 
point  all  the  foul-air  flues  are  made  to  converge  and  enter  a  single 
shaft,  in  connection  with  which  is  a  furnace  or  coil  of  steam  pipe  to 
give  additional  heat  and  ascensional  force  to  the  air. 

The  second  method  is  to  carry  the  foul-air  flues  of  each  story 
horizontally  to  the  central  shaft  which  they  enter  at  the  level  of  the 
ceiling,  which  may  be  termed  aspiration  on  a  level  or  horizontally. 
The  third  method  is  to  carry  all  the  foul-air  flues  downward  to  the 
cellar,  where  they  are  collected  into  a  duct,  or  ducts,  leading  to  the 
central  upcast  shaft.  This  is  the  aspiration  from  below  of  Planat. 
The  fourth  system  is  a  combination  of  the  first  and  third,  the  rooms  in 
the  upper  story  having  their  flues  passing  upward,  while  the  remaining 
floors  are  ventilated  by  flues  passing  downward. 

In  selecting  from  the  various  methods  the  one  to  be  used  in  a 
particular  building,  the  architect  should  be  governed  by  the  following 
considerations: 

first. — It  is  desirable  to  reduce  the  number  of  main  foul-air 
shafts  or  ventilating  stacks  as  much  as  possible.  One  is  better  than 

*P.  Planat,  Cours  de  Construction  Civile,  Premiere  partie.  Chauffage  et 
Ventilation  des  lieux  habites.  Paris,  1880. 


FOUL-AIR    FLUES.  275 

two,  and  there  are  very  few  buildings  in  which  more  than  two  such 
shafts  should  be  used.  With  one  large  chimney  the  friction  is  reduced 
to  a  minimum,  the  arrangements  for  control  of  the  velocity  can  be 
simplified,  and  all  risk  of  one  aspirating  shaft  pulling  against  another 
is  avoided.  The-question  as  to  the  employment  of  one  or  two  shafts 
must  be  determined  by  the  plan  of  the  building  and  the  possibility  of 
placing  the  shaft  in  a  nearly  central  position. 

Second. — In  the  second,  third  and  fourth  systems  above  referred 
to,  the  shaft  will  usually  be  built  of  brick,  and  be  of  nearly  uniform 
diameter  from  the  bottom  up.  It  will  also  in  most  cases  be  convenient 
to  carry  the  smoke  pipe  from  the  heating  apparatus  upward  within  this 
shaft.  Such  a  shaft  as  this  occupies  more  space  than  might  at  first  be 
supposed.  It  will  be  remembered  that  the  velocity  of  the  air  in  it 
should  not  exceed  6  feet  per  second.  If,  then,  it  is  to  give  passage 
to  216  cubic  feet  per  second — which  implies  a  building  of  a  size  to 
accommodate  between  two  and  three  hundred  persons — the  chimney 
must  have  36  square  feet  of  clear  inside  area.  Such  a  shaft  will  prob- 
ably reach  100  feet  in  height,  requiring  thick  walls  at  the  bottom,  and 
it  will  be  found  necessary  to  provide  nearly  100  square  feet  of  area 
for  it. 

In  the  first  system  above  referred  to,  it  is  not  necessary  to  carry 
the  large  central  shaft  up  through  every  floor.  The  shaft  begins  in 
the  attic,  and  may  be  made  of  wood,  if  properly  lined,  or  of  galvanized 
or  boiler  iron,  according  to  its  size. 

Third. — In  the  first  system  the  number  of  flues  in  the  walls  in- 
creases with  the  height;  in  the  third  system  the  reverse  occurs.  In 
other  words,  in  the  third  system  the  walls  are  weakest  below,  just 
where  they  have  the  most  weight  to  carry,  and  therefore  should  be 
thicker  than  when  the  first  system  is  used. 

Fourth. — The  application  of  heat  to  the  central  shafts  can  be  ar- 
ranged more  easily  and  to  much  better  advantage  in  the  third  system 
than  in  either  of  the  others.  During  the  winter  the  heat  needed  for 
this  purpose  can  be  obtained  in  most  cases  from  the  smoke  flue  from 
the  heating  apparatus,  while  in  summer  a  small  furnace  can  easily  be 
connected  with  the  side  of  the  base  of  the  shaft.  As  the  aspirating 
power  of  the  shaft  depends  on  the  height  of  the  heated  column  of  air 
as  well  as  on  the  difference  between  the  temperature  in  the  shaft  and 
that  of  the  external  air,  it  is  evident  that  the  nearer  the  bottom  of  the 
shaft  the  extra  heat  is  applied,  the  greater  will  be  its  efficacy,  bearing 
in  mind  that  it  must  be  applied  at  a  point  above  the  entrance  of  all 
foul-air  flues.  In  the  first  plan  it  will  usually  be  found  most  conven- 


276  FOUL-AIR    FLUES. 

lent  to  apply  the  accelerating  heat  by  means  of  a  coil  of  pipe  lining 
the  shaft  and  heated  by  steam. 

The  difference  in  the  cost  of  maintenance  for  systems  one,  two 
and  three,  has  been  computed  by  Planat  for  a  building  four  stories 
high,  having  a  ventilation  of  39  cubic  feet  per  second. 

He  finds  that  with  system  one,  it  would  be  necessary  to  burn 
seven  pounds  of  coal  per  hour  to  heat  the  shaft;  with  system  two,  5^ 
pounds,  and  with  system  three,  4.1  pounds.  The  third  system  is 
therefore  much  the  least  costly  of  the  three  as  regards  maintenance, 
and  it  also  secures  greater  uniformity  of  action  and  is  more  convenient 
to  manage,  for  which  reasons  it  should  in  most  cases  be  preferred.  In 
an  old  building,  however,  it  is  often  much  easier  to  apply  the  first  sys- 
tem, and  in  some  it  is  the  only  one  which  can  be  used. 

When  system  one  is  employed,  all  foul-air  flues  should  run  in  or 
against  inside  walls  in  order  that  they  may  lose  as  little  heat  as  pos- 
sible. In  system  three  this  is  a  matter  of  less  importance,  although 
in  this  also  it  is  desirable  to  keep  the  foul-air  flues  warm,  but  in  this 
system  it  is  necessary  that  the  central  shaft  shall  be  kept  constantly 
heated,  summer  and  winter.  If  it  be  allowed  to  cool  off  in  summer, 
there  will  probably  be  a  backward  draught  through  the  foul-air  flues 
at  certain  times  during  the  day  when  it  is  cooler  in  the  building  than 
it  is  out  of  doors,  and  it  will  then  be  found  very  difficult  to  start  a  fire 
to  warm  the  shaft.  If  the  building  is  a  high  one  and  has  a  central 
hall  reaching  to  the  roof,  it  is  necessary  to  take  special  care  to  make 
the  upper  part  of  this  hall  as  air-tight  as  possible,  for  otherwise  it  may 
easily  become  a  powerful  ventilating  shaft  and  antagonize  the  appa- 
ratus designed  for  ventilating  purposes,  besides  wasting  a  great  deal 
of  heat. 

It  the  upcast  aspirating  shaft  or  chimney  is  to  be  so  arranged  as 
to  regulate  the  velocity  of  the  current  in  it,  this  should  not  be  done 
by  valves  or  dampers  at  or  near  the  base,  because  if  the  velocity  at  the 
top  is  too  small,  the  draught  may  be  interfered  with  by  winds.  The 
best  arrangement  seems  to  be  to  put  double  valves  at  the  top  so  that 
the  outlet  opening  can  be  closed  more  or  less  at  pleasure.  Fig.  48 
shows  the  plan,  and  Figs.  49,  50,  sections  of  the  tops  of  ward  aspi- 
rating chimneys  in  the  Johns  Hopkins  Hospital  in  which  this  mode  of 
arranging  the  valves  has  been  adopted. 

Within  the  last  50  years  a  vast  amount  of  ingenuity  has  been 
expended  upon  devices  to  be  placed  at  the  mouths  of  tubes,  flues,  or 
shafts,  for  the  purpose  of  giving  direction  to  air  currents  passing 
through  them,  or  of  enabling  the  wind  to  produce,  accelerate,  or  pre- 


OUTLET    VENTILATORS. 


277 


vent  such  currents.  These  devices,  commonly  known  as  ventilators, 
have  of  late  been  patented  in  endless  variety,  and  about  a  dozen  new 
ones  are  added  to  the  list  every  year. 

The  outlet  ventilators,  which  properly  include  all  forms  of  chim- 
ney caps  or  terminals  for  smoke,  as  well  as  foul-air  flues,  were  prob- 
ably first  planned  to  prevent  the  entrance  of  rain  or  snow  into  the 
flues,  and  this  is  still  one  of  their  most  important  uses.  Their  action 
depends  upon  two  facts  connected  with  the  movement  of  fluids. 

The  first  of  these  is  what  is  sometimes  called  the  law  of  the  lateral 
communication  of  motion  in  fluids — the  fact  that  a  fluid  in  motion 
tends  to  communicate  motion,  in  the  same  direction,  to  other  portions 
of  fluid  immediately  connected  with  it. 


FIG.  48. 


FIG.  49- 


FIG. 


50. 


The  second  fact  is  the  tendency  of  air  to  adhere  to  surfaces. 
When  a  current  of  air  strikes  a  surface  it  is  not  reflected  at  an  angle 
equal  to  the  angle  of  incidence,  as  a  ray  of  light  or  a  billiard  ball 
would  be,  but  it  is  spread  out  in  a  thin  layer  upon  the  surface.  In  a 
valuable  series  of  papers  by  F.  Savart,  published  in  the  Annales  de 
Chimie  et  de  Physique  for  1833,  it  is  shown  that  "  When  a  jet  of  water 
strikes  a  truncated  cone  perpendicularly  to  its  axis,  and  just  above  its 
lower  base,  it  spreads  out,  covering  more  than  half  its  surface,  and, 
rising  upward,  leaves  its  upper  base  in  a  continuous  sheet,  vertically, 
in  a  plane  nearly  coinciding  in  direction  with  that  of  the  sides  of  the 
cone,  and  horizontally,  nearly  in  the  direction  of  tangents  to  the  sur- 
face of  the  cone,  while  a  small  portion  only  of  the  fluid  forms  two 


278  OUTLET    VENTILATORS. 

small  streams,  which  drop  down  from  those  two  points  of  the  lower 
base  of  the  cone  which  are  at  right  angles  with  the  original  direction 
of  the  jet. 

''When  a  jet  meets  a  plane  at  its  center  and  perpendicularly,  it 
forms  a  continuous  sheet  over  the  whole  surface,  thin  in  the  center 
and  thicker  towards  the  circumference. 

"  Both  the  direction  and  continuity  of  this  sheet  are  preserved  far 
beyond  the  borders  of  the  circular  plane,  where  its  edge  is  thin,  but  it 
follows  more  or  less  the  direction  of  the  curve  of  the  edge,  if  it  is 
thick  and  rounded. 

"  When  a  jet  of  air  infringes  upon  a  surface  of  limited  extent,  the 
atmospheric  pressure  upon  the  opposite  side  of  the  surface,  in  conse- 
quence, of  the  lateral  communication  of  motion,  is  diminished,  and  a 
current  will  be  established  through  a  tube,  one  of  the  extremities  of 
which  is  placed  m  the  point  of  diminished  pressure,  and  the  other  be- 
yond the  borders  of  the  surface.  This  is  the  important  principle  upon 
which  the  efficiency  of  ventilators  and  chimney  tops  depends;  it  is  also 
important  in  its  bearing  on  the  position  of  the  mouths  of  air-trunks  for 
hot-air  furnaces;  if  the  mouth  be  placed  in  a  point  of  diminished  press- 
ure, on  the  leeward  side  of  a  building,  air  may  pass  outward,  especially 
from  apartments  on  the  windward  side  of  the  house." 

As  Dr.  Wyman  points  out,  "  A  simple  demonstration  of  these  pro- 
positions may  be  obtained  by  means  of  a  card  and  candle.  If  a  blast 
from  the  mouth  be  directed  obliquely  against  a  card,  the  flame  of  a 
lighted  candle  will  be  drawn  towards  the  card,  on  whatever  side  of  it 
the  candle  is  held.  Increasing  or  diminishing  the  velocity  of  the  blast 
does  not  change  the  direction  assumed  by  the  flame,  but  only  the 
velocity  with  which  it  is  drawn  toward  the  card. 

"  If  the  blast  be  directed  perpendicularly  upon  the  center  of  the 
card,  the  flame  when  passed  around  the  edge  of  the  card  will  be 
driven  outward  at  all  points;  and  if  the  candle  be  held  near  the  blast 
and  at  a  little  distance  from  the  plane  surface,  the  flame  will,  in  virtue 
of  the  lateral  communication  of  motion,  be  drawn  toward  the  surface,, 
and  yet,  by  the  current  air  close  to  and  parallel  with  the  card,  it  will 
be  prevented  from  reaching  it.  A  strong  flame  may  thus  be  made  to 
play  apparently  with  great  force  upon  the  hand,  and  yet  not  burn  it. 
An  illustration  of  this  principle  may  often  be  observed  in  the  narrow 
pathway,  so  convenient  for  foot  passengers,  found  after  a  snow  storm 
on  the  windward  side  of  a  high  and  close  fence." 

In  accordance  with  these  principles,  it  is  easy  to  see  that  when  a 
current  of  air  flows  across  the  open  mouth  of  a  simple  cylindrical  tube 


OUTLET    VENTILATORS.  279 

it  must  exert  a  certain  aspirating  power  upon  the  tube,  or  that  a  small 
stream  of  air  directed  through  a  large  tube  tends  to  set  in  motion  the 
entire  contents  of  the  tube,  upon  the  principle  of  the  well-known  Gif- 
fard's  injector. 

The  object  of  all  cowls  is  to  present  such  a  surface  to  the  wind 
that  the  sheet  of  moving  air  produced  shall,  on.  leaving  the  surface,  be 
moving  at  such  an  angle  to  the  column  of  air  contained  in  the  flue  as 
to  exert  the  strongest  aspirating  effect  upon  it.  The  strength  of  this 
aspirating  effort  varies,  within  certain  limits,  with  the  velocity  of  the 
currents,  and  also  with  the  angle  which  is  made  by  the  current  with 
the  axis  of  the  flue. 

Some  of  these  cowls  are  made  to  revolve  with  the  wind;  others  are 
fixed,  and  present  in  every  direction  the  same  form  of  surface  and  open- 
ing. As  Dr.  Wyman  remarks,  there  are  few  objects  upon  which  so 
much  time  has  been  spent  and  misspent;  and  their  great  variety  and 
the  constant  changes  in  their  arrangement  are  proofs  that  more  is  ex- 
pected of  them  than  they  accomplish,  and  that  the  principles  on 
which  they  act  are  not  well  understood. 

The  effect  of  outlet  cowls,  when  placed  at  the  top  of  vertical  shafts 
or  flues,  has  been  the  subject  of  several  sets  of  experiments. 

The  first  of  these  to  which  I  shall  refer  were  made  in  1842  by 
Messrs.  Ewbank  and  Mott,  and  the  results  were  reported  by  them  in 
the  Journal  of  the  Franklin  Institute,  3d  series,  Vol.  IV.,  1842,  p.  104. 

They  directed  a  strong  current  or  blast  of  air  from  bellows  across 
the  top  of  a  glass  tube,  an  inch  and  a  quarter  in  diameter  and  28  inches 
long.  The  lower  end  of  this  tube  was  dipped  into  a  vessel  of  water, 
and  on  the  upper  end  were  successively  placed  tin  models  of  the  va- 
rious forms  of  cowls  experimented  on. 

The  greatest  rise  of  the  water  column,  showing  the  strongest  as- 
piration, was  obtained  by  the  use  of  a  short  conical  tube,  placed  at 
right  angles  to  the  glass  tube,  and  having  the  blast  directed  through 
it  from  the  small  toward  the  large  end. 

These  experiments,  however,  cannot  be  considered  to  be  of  much 
value,  for  the  cross  current  used  was  stronger  than  a  violent  hurricane, 
and  it  is  not  safe  to  rely  upon  obtaining  with  full-sized  flues  the  same 
results  as  are  shown  by  glass-tube  models  in  the  movements  of  air 
currents. 

A  much  more  extended  and  valuable  series  of  experiments  upon 
the  effect  of  various  forms  of  outlet  cowls  was  made  by  a  committee 
appointed  for  this  purpose  by  the  American  Academy  of  Arts  and 
Sciences.  The  report  of  this  committee,  to  which  I  have  already  re- 


280  OUTLET    COWLS. 

ferred,  was  prepared  by  Dr.  Morrill  Wyman,  and  will  be  found  in  Vol. 
I.,  of  the  Proceedings  of  the  Academy,  Boston,  1848,  p.  307. 

In  these  experiments  a  constant  current  of  air,  produced  by 
means  of  a  revolving  fan,  was  used  to  produce  an  induced  current  in 
a  tube,  having  its  long  axis  at  right  angles  to  that  of  the  blast; 
the  velocity  of  the  current  thus  produced  being  measured  directly, 
and  not  by  its  power  of  sustaining  a  weight,  or  head  of  water, 
or  other  statical  effect,  which  method  the  committee  remarks  is 
decidedly  objectionable.  "  Such  a  measure  gives  the  correct 
value  of  the  initial  force  or  tendency  to  establish  a  current  in  a 
chimney  in  which  there  is  no  actual  movement ;  but  it  does  not 
indicate  the  velocity  of  the  current  which  will  be  the  final  result 
of  the  action  of  the  ventilator,  nor  is  it  any  measure  of  this 
final  velocity  when  ventilators  of  different  construction  are  compared 
together.  Mechanics  and  engineers  are  familiar  with  the  differences 
between  statical  and  dynamical  effects  of  a  force.  In  the  air  pump 
the  dynamical  value  of  any  amount  of  exhaustion  is  equal  to  the  power 
required  to  produce  it,  and  is,  therefore,  proportioned  to  the  magni- 
tude of  the  receiver  when  other  circumstances  are  the  same;  whereas, 
its  statical  power,  or  its  power  to  sustain  a  head  of  water,  is  wholly 
independent  of  the  magnitude  of  the  receiver,  and  proportioned  solely 
to  the  tension  of  the  air  within  it." 

To  measure  the  current,  a  leaden  pipe  1.25  inches  in  diameter  and 
53  feet  in  length  was  placed  near  and  a  few  inches  below  the  mouth  of 
the  blowing  machine.  In  the  mouth  of  the  trunk,  attached  to  the 
blowing  machine,  was  a  tube  of  tinned  iron  of  the  same  diameter  as 
the  pipe,  and  bent  at  a  right  angle;  the  upright  branch,  about  6  inches 
long,  reaching  to  the  middle  of  the  mouth,  while  the  horizontal  portion, 
about  5  inches  in  length,  reached  to  within  2.5  inches  of  the  end  of  the 
leaden  pipe.  Each  ventilator,  when  examined  and  tested,  was  placed 
upon  the  upright  portion  of  this  tube.  For  this  purpose  the  ventilator 
had  through  it,  or  attached  to  its  side,  a  corresponding  tube  of  the 
same  diameter.  The  velocity  of  the  blast  was  10.36  feet  per  second, 
or  7.06  miles  per  hour.  With  the  blast  passing  across  the  top  of  a 
perpendicular  fixed  tube  cut  at  right  angles,  the  velocity  of  the  induced 
current  was  0.728  feet  per  second;  with  a  straight  tube,  cut  off  ob- 
liquely at  an  angle  of  45  degrees,  opening  turned  from  the  blast,  the 
velocity  was  1.325;  with  a  truncated  cone,  the  velocity  was  1.71  feet 
per  second;  with  a  cone  with  cap,  as  laid  down  by  De  Lyle  St.  Mar- 
tin, lieutenant  in  the  French  Navy  in  1788  (see  Fig.  51),  the  velocity 
was  1.56.  St.  Martin's  cone  without  the  cap  gave  a  velocity  of  2.21. 


OUTLET    COWLS.  28l 

The  cone  was  proposed  as  the  proper  form  for  the  chimney  top, 
and  an  account  of  its  application  was  published  by  Count  Cisalpin 
about  100  years  ago.  The  adjoining  figure  (52),  is  an  elevation  from 
the  perspective  view  given  in  the  memoir.  This,  slightly  modified 
(Fig.  53),  is  what  is  generally  known  as  the  Emerson  ventilator,  and  is 
one  of  the  best  of  all  the  various  forms  of  cowls.  The  best  form  of 
cowl,  as  shown  by  the  report  of  the  committee  just  referred  to,  and  the 
one  which  I  prefer  for  all  upcast  shafts,  is  shown  in  Fig.  54.  There 
are  now  no  patents  upon  any  of  the  cowls  just  described. 


FIG.  51.  FIG.  52. 

This  matter  of  terminals  of  foul  air  and  smoke  flues  occupies 
such  a  prominent,  although  for  the  most  part  wholly  unmerited,  place 
in  the  literature  of  ventilation,  and  so  much  stress  is  laid  upon  the 
merits  of  this  or  that  particular  form  of  cap  or  cowl,  not  only  by  pat- 
entees, but  by  some  architects,  that  a  few  more  words  on  the  subject 
seem  necessary. 

Dr.  Wyman  remarks  that  in  a  strong  wind  any  cap  will  be  effect- 
ual which  prevents  the  wind  from  beating  down  the  chimney.  "  In  a 


FIG.  53.  FIG.  54. 

lignt,  unsteady  wind,  the  time  when  the  cap  is  most  needed,  it  is  sub- 
ject to  a  disadvantage  which  it  is  difficult  to  obviate.  The  friction  is 
always  considerable,  and,  under  the  circumstances  just  mentioned,  the 
opening  of  the  cowl  will  often  be  directed  toward  the  wind;  in  this 
position  the  wind  will  have  but  little  influence  upon  the  vane,  and  the 
smoke,  if  the  draught  is  feeble,  will  be  driven  into  the  apartment- 


282  OUTLET    COWLS. 

"  The  steadiness  of  the  cowl  may  be  increased  by  making  the 
vane  double,  the  two  sides  forming  an  angle  of  10  or  15  degrees  (<). 
The  single  vane  in  common  use,  receiving  no  pressure  from  the  wind 
when  in  its  direction,  has  the  same  tendency  to  flap  as  a  loosened 
sail.  The  friction  may  be  diminished  by  nicer  workmanship,  and  the 
noise  lessened  by  allowing  the  cowl  to  run  in  leather  collars  ;  but 
the  objection  we  have  alluded  to  will  only  be  diminished,  not 
removed." 

Dr.  Wyman  speaks  favorably  of  a  form  of  cowl  which  consists  of  a 
conical  cap  balanced  on  a  point  so  that  it  can  be  tilted  in  any  direc- 
tion. The  wind  blowing  upon  it  depresses  the  side  upon  which  it 
strikes,  and  at  the  same  time  elevates  the  opposite  side. 

In  1878  a  series  of  experiments  were  made  at  the  Royal  Observa- 
tory, Kew,  England,  upon  ventilating  exhaust  cowls,  by  a  committee 
composed  of  W.  Eassie,  Rogers  Field,  and  Douglas  Galton,  whose 
names  are  a  sufficient  warrant  for  the  care  with  which  the  tests  were 
made.  The  cowls  thus  tested  were  the  air-pump  ventilator  of  Boyle 
and  the  injector  cowl  of  Mr.  Lloyd,  which  is  a  fixed  cowl  like  that 
used  by  Captain  Liernur,  of  Amsterdam.  Four  upright  iron  tubes, 
each  6  inches  in  diameter  and  12  feet  long,  were  so  arranged  as  to  re- 
ceive equal  air  supply  below,  and  the  same  exposure  to  wind  above  the 
roof  of  the  building  in  which  they  were  placed,  and  above  which  they 
projected  about  2  feet.  On  three  of  these  tubes  the  cowls  above 
mentioned  were  fixed,  while  the  fourth  was  left  as  a  plain  open  tube, 
to  serve  as  a  standard  of  comparison.  The  results  are  given  in  the 
following  report,  which  is- a  model  of  brevity  and  clearness  : 

"  The  sub-committee  appointed  at  Leamington  to  test  the  ventilat- 
ing exhaust  cowls  beg  to  report  that  they  have  given  the  matter  their 
most  careful  attention,  and  carried  out  at  the  Royal  Observatory, 
Kew,  an  elaborate  series  of  about  100  experiments,  on  seven  different 
days,  at  different  times  of  the  day,  and  under  different  conditions  of 
wind  and  temperature.  After  comparing  tne  cowls  very  carefully  with 
each  other,  and  all  of  them  with  a  plain  open  pipe  as  the  simplest, 
and,  in  fact,  only  available  standard,  the  sub-committee  find  that  none 
of  the  exhaust  cowls  cause  a  more  rapid  current  of  air  than  prevails 
in  an  open  pipe  under  similar  conditions,  but  without  any  cowl  fitted 
on  it.  The  only  use  of  the  cowls,  therefore,  appears  to  be  to  exclude 
rain  from  the  ventilating  pipes  ;  and  as  this  can  be  done  equally,  if 
not  more  efficiently,  in  other  and  similar  ways  without  diminishing 
the  rapidity  of  the  current  in  the  open  pipe,  the  sub-committee 
are  unable  to  recommend  the  grant  of  the  medal  of  the  Sanitary 


OUTLET    COWLS.  283 

Institute  of  Great  Britain  to  any  of  the  exhaust  cowls  submitted  to 
them  for  trial." 

Of  course,  this  report  was  by  no  means  satisfactory  to  the  in- 
ventors and  proprietors  of  patent  cowls,  and  in  this  respect  it  corre- 
sponds with  the  previous  reports  to  which  I  have  referred  before. 
Each  inventor  obtains  very  different  results  from  his  own  experi- 
ments, and  there  seems  to  be  no  immediate  prospect  of  reconciling  the 
discrepancies. 

Mr.  Hellyer,  in  the  second  edition  of  his  work  on  "  Plumbing  and 
Sanitary  Houses,"  has  an  interesting  chapter  headed  "  Ventilation,  or 
Cowl  Testing,  but  not  at  Kew,"  in  which  he  gives  the  results  of  a 
number  of  experiments  made  with  cowls  of  different  kinds.  He 
concludes  that,  while  the  power  of  a  cowl  to  cause  an  upcast  of  air 
through  the  pipe  is  not  so  great  as  some  suppose,  it  certainly  is  greater 
than  the  report  of  the  Kew  Committee  would  lead  us  to  believe. 

He  "  considers  that  cowls  should  be  fixed  on  all  ventilating  pipes 
for  foul  air,  not  so  much  for  assisting  the  up  draught  as  for  pre- 
venting a  down  draught^  especially  where  the  air  blown  down  through 
such  ventilating  pipes  would  come  out  near  a  window  or  door, 
where  it  should  be  sucked  into  the  house."  (The  italics  are  in  the 
original.) 

His  experiments  were  made  with  two  4-inch  lead  pipes,  each  about 
32  feet  long,  the  tops  being  about  6  feet  above  the  roof  and  4  feet 
apart.  In  one  of  the  chief  systems  of  testing,  the  bottoms  of  these 
pipes  were  connected  by  a  pipe  in  the  form  of  the  letter  U,  so  arranged 
that  an  anemometer  could  be  inserted  and  observed  through  a  glass 
door.  By  this  apparatus  a  cowl  can  be  tested  against  another  cowl  or 
against  an  open  pipe  on  what  the  author  calls  the  "  Pull,  devil,  pull, 
beggar  principle." 

Mr.  Hellyer  concludes  that  the  best  cowls  are  better  than  open 
pipes;  that  the  relative  value  of  various  cowls  varies  according  to  the 
different  states  of  the  atmosphere;  that,  on  the  whole,  the  best  cowl  is 
one  of  Mr.  Buchan's,  and  that  of  Mr.  Hellyer's  comes  second. 

Many  attempts  have  been  made  to  combine  the  inlet  and  outlet  in 
the  same  ventilator,  and  this  either  with  or  without  connecting  them 
with  the  heating  apparatus.  Of  those  combining  the  inlet  and  outlet 
in  a  single  tube  or  shaft,  which  is  intended  or  supposed  to  be  entirely 
independent  of  the  heating,  the  principal  forms  are  the  ventilators  of 
Watson,  Muir,  M'Kinnell,  and  Macdondald;  the  first  three  of  which 
are  described  and  figured  in  most  English  works  on  hygiene  or  on 
ventilation.  All  of  these  are  intended  to  be  inserted  in  the  center  of 


284 


DOUBLE-TUBE    VENTILATORS. 


the  ceiling  of  the  room  or  space  to  be  ventilated,  and  the  best  of  them  is 
probably  the  double  tube  of  M'Kinnell  (Fig.  55).  "  It  consists  of  two 
cylinders,  one  encircling  the  other,  the  area  of  the  inner  tube  and  encir- 
cling ring  being  equal.  The  inner  one  is  the  outlet  tube;  it  is  so  because 
the  casing  of  the  other  tube  maintains  the  temperature  of  the  air  in  it; 
and  it  is  also  always  made  rather  higher  than  the  other.  The  outer 
cylinder  or  ring  is  the  inlet  tube;  the  air  is  taken  at  a  lower  level  than 
the  top  of  the  outlet  tube,  and  when  it  enters  the  room  it  is  deflected 
toward  and  spread  over  the  ceiling  by  a  flange  placed  on  the  bottom 
of  the  inner  tube.  Both  tubes  can  be  closed  by  valves." 

The  Macdonald  ventilator  is  recommended  in  the  last  edition  of 
Parkes*  "  Hygiene,"  where  it  is  figured  and  described.  It  is  similar  to 
the  M'Kinnell  tubes,  but  has  a  fan  within  the  tube  which  is  driven  by 


FIG.  55. 


another  fan  placed  on  the  top  of  the  tube,  the  result  being  that  no 
reversal  of  the  current  is  possible  so  long  as  there  is  wind  enough  to 
give  motion  to  the  fan.  It  seems,  however,  rather  complicated  and 
costly.  By  making  the  motile  fan  much  larger,  and  self-regulating  to 
secure  a  constant  velocity,  as  is  done  in  many  of  the  modern  American 
windmills,  this  principle  might  be  made  useful  in  some  cases. 

These  double-tube  ventilators  are  especially  applicable  to  build- 
ings containing  but  one  room,  and  where  doors  and  windows  are  very 
rarely  opened,  but  they  are  useless  in  dwelling  houses.  When  a  dcor 
or  window  is  opened  in  the  room  in.  which  they  are  placed,  their  action 
either  ceases  altogether  or  they  become  upcast  shafts — while,  if  there 
is  an  open  fireplace  in  the  room,  they  become  inlets. 


DOUBLE-TUBE    VENTILATORS.  285 

To  illustrate  the  use  which  may  be  made  of  these  tube  ventilators, 
under  exceptional  circumstances,  the  reader  may  consult  a  paper  by 
Dr.  J.  N.  Radcliffe,  which  will  be  found  in  full  in  the  Sanitary  Review, 
for  1858,  vol.  4,  p.  343.  During  the  Crimean  War,  Dr.  Radcliffe  had 
occasion  to  take  charge  of  a  number  of  sick,  placed  in  a  small  shed,  lit 
by  two  small  windows,  the  sashes  of  which  were  fixed,  the  only  opening 
for  either  ingress  or  egress  of  air  being  the  door.  This  shed  contained 
13  patients.  It  had  a  tiled  and  sloping  roof,  and  a  ceiling  at  a  height 
of  about  10  feet.  The  days  and  nights  were  somewhat  chilly,  and  any 


FIG.  56. 


attempt  to  introduce  fresh  air  from  the  door,  windows  or  walls  was 
useless.  Large  openings  were  made  in  the  ceiling  and  roof,  and  above 
the  opening  in  the  roof  a  shaft  was  erected,  divided  by  a  partition  and 
covered  by  a  roof,  large  enough  to  prevent  the  intrusion  of  wind  or 
rain.  The  result  was  entirely  satisfactory  and  there  was  no  discomfort. 
Dr.  Radcliffe  thinks  that  much  of  this  satisfactory  result  was  due  to  the 
fact  that  the  ventilating  tubes  did  not  communicate  directly  with  the 
room,  but  with  the  attic,  which  formed  an  air  chamber,  the  ceiling 
acting  as  a  diaphragm  between  this  chamber  and  the  room. 


286  SYPHON    VENTILATORS. 

The  inlet  and  outlet  are  combined  in  connection  with  the  heating 
apparatus  in  what  is  known  as  Barker's  patent.  In  this  system  the 
hot-air  and  the  foul-air  registers  are  in  one  frame,  the  former  being 
above  the  latter.  The  lower  part  of  the  foul-air  flue  thus  passes 
through  the  upper  or  terminal  portion  of  the  fresh-air  flue  by  which  it 
is  warmed  (Fig.  56). 

The  results  obtained  by  this  system  in  a  ward  of  a  hospital  in 
Philadelphia,  1  have  found  to  be  not  satisfactory.  In  cold  weather  a 
strong  current  is  developed  in  the  outlet  flue,  but  the  distribution  of 
air  within  the  room  does  not  seem  satisfactory;  while  with  the  exter- 
nal temperature  of  50°  F.,  the  hot-air  supply  is  in  great  part  shut  off 
to  prevent  overheating. 

One  of  the  many  fallacies  and  errors  which  have  from  time  to 
time  been  urged  by  writers  on  ventilation,  and  with  which  it  is  desir- 
able that  the  architect  and  sanitary  engineer  should  be  acquainted, 
since  they  are  constantly  coming  up  afresh  in  the  form  of  a  patent  or 
of  a  letter  of  advice  to  the  daily  press,  is  that  of  the  effect  of  syphons 
or  syphon-like  arrangements  as  exit  flues  for  foul  air,  and  of  the  effect 
of  Archimedean  screw  ventilators. 

A  pamphlet  has  appeared  entitled  "  Ventilation  by  Means  of  the 
Patent  Pneumatic  or  Air-Syphon  with  or  without  Artificial  Heat," 
which  begins  as  follows  : 

"  The  process  does  not  require  a  fire,  or  any  other  artificial  heat, 
or  moving  power.  It  consists  of  the  practical  application  of  operations 
constantly  taking  effect  in  the  atmosphere,  which  cause  a  current  to 
take  a  place  through  an  inverted  syphon,  having  one  of  its  branches 
considerably  longer  than  the  other  (whether  it  be  in  the  open  air 
or  with  the  shorter  branch  communicating  with  a  room  or  other 
place),  into  which  the  air  enters  at  the  orifice  of  the  short  branch, 
and  is  discharged  by  that  of  the  longer.  This  process  is  not 
prevented  by  making  the  short  branch  hotter  than  the  long.  When 
it  is  proposed,  in  the  hereafter-described  arrangements,  to  use 
the  chimney  as  the  long  branch,  it  is  because  of  there  being  such 
a  channel  at  hand,  and  because  it  is  capable  of  serving  a  double 
purpose  when  the  season  requires  fire,  and  is  conveniently 
available  for  that  single  purpose  (ventilation)  when  fire  is  not 
required." 

Upon  this  absurd  claim  it  is  only  necessary  to  remark  that  if  a 
syphon  could  of  itself  either  create  or  increase  a  current  of  air,  the 
problem  of  perpetual  motion  would  be  solved,  and  man  would  be  able 
to  create  force. 


J 

• 
OUTLET    COWLS.  287 

If  there  is  a  current  of  air  in  a  syphon,  it  is  because  some  force  is 
producing  it,  and  in  the  great  majority  of  cases  this  force  is  due  to  a 
difference  in  temperature  between  the  bodies  of  air  at  the  extremities 
of  the  tube. 

With  regard  to  the  various  forms  of  Archimedean  screw  ventila- 
tors, as  usually  made  they  have  no  effect,  unless  driven  by  power  in- 
dependent of  the  wind.  In  calm  weather,  of  course,  all  forms  of  cowls 
are  entirely  inoperative,  except  as  furnishing  more  or  less  obstruction 
to  the  free  egress  of  air;  and  on  a  still,  warm  day,  when  the  tem- 
perature within  a  large  building  may  be  several  degrees  lower  than 
that  out  of  doors,  there  will  be  a  tendency  to  a  reversal  of  the  current 
and  to  down  draughts  through  any  form  of  cowl  that  can  be  devised. 

It  often  seems  to  be  supposed  by  those  advocating  the  use  of  this 
or  that  particular  cowl,  that  the  cowl  itself  has  some  mysterious  effect 
in  producing  currents  of  air  within  it  independent  of  wind  or  of  differ- 
ences of  temperature,  and  that,  therefore,  if  enough  cowls  are  pro- 
vided we  can  make  sure  of  the  effect  desired 'under  all  circumstances. 
This  is,  of  course,  not  the  case,  nor  does  it  by  any  means  follow  that 
the  use  of  two  or  more  cowls  on  a  building  will  produce  more  effect 
than  one;  in  fact,  the  effect  may  be  just  the  reverse.  For  example,  I 
have  seen  a  large  three-story  building  in  which  the  foul-air  flues  from 
the  several  floors  terminated  in  the  open  space  of  the  attic,  and  then 
half  a  dozen  patent  cowl  ventilators  were  placed  in  the  roof  to  com- 
plete the  arrangement.  The  result  was  that  the  several  cowls  pulled 
against  each  other,  and  as  they  were  only  9  inches  in  diameter,  the  re- 
sult was  sometimes  almost  inappreciable.  Had  a  single  shaft,  about 
3  feet  in  diameter  and  properly  capped,  been  inserted,  much  better 
results  would  have  been  obtained,  although  this  plan  of  using  the 
whole  attic  as  a  foul-air  reservoir  is  one  that  should  be  condemned 
under  all  circumstances. 


CHAPTER  XIII. 

VENTILATION    OF    MINES. 

IN  the  preceding  chapters  have  been  stated  the  general  principles 
which  should  govern  arrangements  for  ventilation,  and  we  may  now 
proceed  to  consider  some  of  their  practical  applications.  Among  these, 
one  of  the  greatest  importance  is  that  of  the  ventilation  of  mines,  and 
especially  of  coal  mines.  In  these  the  problem  is  not  complicated  by 
the  need  for  varied  quantities  of  artificial  heat  at  different  seasons  of 
the  year,  which  forms  such  an  important  feature  in  the  arrangements 
for  ventilation  of  dwellings,  but,  on  the  other  hand,  the  mechanical 
problems  are  usually  more  complicated  and  difficult  and  the  details 
require  constant  readjustment. 

In  many  coal  mines  it  is  absolutely  necessary  to  provide  special 
ventilation,  in  order  to  prevent  explosions  from  fire  damp,  but  it  should 
be  supplied  in  all  mines  for  the  sake  of  the  -health  of  the  men  and 
animals  employed  in  them.  In  the  so-called  fiery  mines,  where  abun- 
dant and  constant  ventilation  is  necessary  to  prevent  accidents,  the 
health  of  the  workmen  is  as"  a  rule  better  than  in  those  mines,  whether 
of  coal  or  of  metal,  where  such  abundant  supply  of  fresh  air  is  not 
given  because  it  is  not  compulsory. 

The  earliest  method  of  forced  ventilation  of  a  mine  shaft  or 
gallery,  appears  to  have  been  by  "  the  diligent  shaking  of  a  piece  of 
cloth"  as  described  and  figured  in  the  treatise  of  George  Agricola,  a 
copy  of  whose  plate  is  given  in  Fig.  57,  A  being  the  level  and  B  the 
cloth  shaken  by  two  men. 

The  air  of  mines  is  rendered  impure  by  the  products  of  respiration 
and  other  exhalations  of  the  men  and  animals  employed  in  them,  by 
the  products  of  combustion  of  candles  or  lamps,  by  the  gases  evolved 
from  the  surfaces  of  the  mine  or  entering  through  fissures,  including 
more  especially  carburetted  hydrogen,  carbonic  acid,  and  sulphuretted 
hydrogen,  and  by  dusts,  which  may  be  directly  poisonous  as  in  the 
Case  of  arsenic  or  mercury,  or  may  be  mechanically  injurious  as  in  the 
case  of  coal  dust,  or  of  smoke  from  powder  blasts.  The  gas  which  has 
been  of  chief  importance  in  promoting  mine  ventilation  is  carburetted 


FIRE    DAMP. 


289 


hydrogen,  CH4,  known  also  as  marsh  gas,  fire  damp,  methane  or 
methyl  hydride,  and  is  found  chiefly  in  coal  mines,  although  it  has 
also  been  met  with  in  salt  mines.  It  is,  as  a  rule,  more  abundant  in 
deep  mines  than  in  shallow  ones,  and  in  European  than  in  American 
mines.  It  is  supposed  to  exist  in  a  state  of  tension  in  the  pores  of  the 
coal,  and  escapes  from  the  fresh  surfaces  exposed  in  working.  If 


FIG. 


abundant,  it  escapes  with  a  hissing  or  bubbling  sound,  and  such  coal 
is  called  "  singing  coal."  It  also  collects  under  pressure  in  fissures  in 
the  coal,  which  when  large  are  known  as  "blowers."  After  an  ex- 
posed surface  of  coal  has  stood  for  a  few  days  the  evolution  of  fire 
damp  greatly  diminishes  or  ceases,  and  hence,  in  a  mine  which  pro- 
duces this  gas  the  quantity  given  off  depends  to  a  great  extent  on  the 


290  AIR  SUPPLY  FOR  MINES. 

amount  of  fresh  surface  daily  exposed,  and  thus  is  proportional  to  the 
daily  output.  When  mixed  with  atmospheric  air  in  proportions  of 
from  i  to  7  to  i  to  12,  it  forms  a  violently  explosive  mixture 
which,  when  fired,  suddenly  expands  to  1,700  times  its  former  volume, 
or,  if  confined  may  produce  a  pressure  of  200  pounds  to  the  square 
inch,  with  a  rise  of  temperature  to  over  1,200°  F.  The  result  of  such 
an  explosion  is  not  only  the  shattering  and  burning  of  objects  in  the 
vicinity,  but  the  production  of  a  mixture  of  carbonic  acid,  nitrogen 
and  watery-vapor  known  as  the  after  damp  which  is  irrespirable  and 
fatal  to  animd  life.  It  is  lighter  than  atmospheric  air  and  hence  rises 
to  the  upper  part  of  galleries  and  pits.  It  does  not  begin  to  affect  the 
flame  of  a  lamp,  to  "show,"  as  the  miners  say,  until  it  forms  about 
3  per  cent,  of  the  mixture  with  air,  hence  it  is  often  present  to 
nearly  that  amount  in  the  air  inhaled,  but  nothing  is  known  as  to  the 
effects  produced  by  breathing  air  containing  from  T  to  2  per  cent,  of  it, 
and  they  are,  at  all  events,  not  soon  perceptible. 

One  of  the  first  questions  to  be  settled  in  planning  for  the  venti- 
lation of  a  given  mine  is  the  quantity  of  air  required,  and,  unlike 
buildings,  this  cannot  be  determined  once  and  for  all,  but  must  change 
with  the  progress  of  the  work.  In  some  of  our  States  the  minimum 
quantity  is  fixed  by  law,  in  relation  to  the  number  of  men  and  animals 
employed  in  the  mine,  the  quantity  specified  being  usually  100  cubic 
feet  of  air  per  minute  per  man.  In  Pennsylvania  200  cubic  feet  per 
minute  per  man  are  required.  In  Colorado  and  Kentucky  the  law 
requires  that  for  each  mule  or  horse  500  cubic  feet  per  minute  must  be 
furnished,  and  in  Illinois  and  Washington,  600  cubic  feet  to  each 
animal  are  required. 

This  mode  of  estimating  the  quantity  of  air  required  to  maintain 
health  and  the  combustion  of  the  lamps,  although  useful  as  a  basis  for 
calculations,  is  entirely  inadequate  to  give  the  real  needs  of  a  given 
coal  mine  in  which  fire  damp  either  is  being,  or  may  be  expected  to 
be  given  off.  To  prevent  accidents,  the  quantity  of  air  must  not  only 
be  sufficient  to  prevent  perceptible  odors,  but  it  must  be  sufficient  to 
dilute  the  fire  damp  so  that  the  mixture  will  produce  no  visible  effect 
on  the  flame  of  a  lamp,  and  hence  the  more  of  this  gas  given  off 
in  a  mine,  the  more  air  must  be  supplied.  The  amount  of  gas  given 
off  increases,  other  things  being  equal,  with  the  amount  of  fresh  sur- 
face of  coal  exposed,  and  this  varies  with  the  daily  output,  hence  the 
rule  sometimes  referred  to  that  from  100  to  200  cubic  feet  of  air 
per  minute  should  be  furnished  for  every  ton  of  coal  extracted 
dailv. 


AIR    SUPPLY    FOR    MINES.  291 

In  a  paper  read  before  the  Society  of  Engineers  by  Mr.  George 
G.  Andre,  the  quantity  of  air  required  for  a  dry  mine  making  compar- 
atively little  gas  is  fixed  at  i  cubic  foot  of  air  per  second  for  every 
100  square  yards  of  surface.  This,  being  the  minimum  amount, 
he  states  is  analogous  to  the  breaking  strain  of  materials  and 
must  be  multiplied  by  a  factor  of  safety  which  will  vary  from  2  to  6. 
If  there  is  comparatively  little  fire  damp,  and  the  mine  is  not  very  wet, 
he  takes  the  factor  of  safety  at  3,  his  mode  of  calculation  being  as 
follows:  "Suppose  we  have  to  ventilate  a  mine  in  which  the  air 
courses  have  a  total  length  of  2,000  yards,  giving  a  total  surface  of,  say, 
14,000  square  yards,  and  that  the  number  of  men  and  horses  are  100 
and  10,  respectively  ;  "  he  allows  to  the  men  a  cubic  foot  for  respira- 
tion, a  cubic  foot  for  the  removal  of  perspiration,  and  a  cubic  foot  for 
his  lamp,  or,  in  all,  3  cubic  feet  per  minute  ;  while  for  the  horses 
he  allows  12  cubic  feet  per  minute.  The  men  and  animals  in  this 
mine  will  then  require  420  cubic  feet  per  minute,  and  the  vapors, 
gases,  etc.,  will  require  140  cubic  feet  per  second,  or  8,400  cubic  feet 
per  minute,  (8,400  -j-  420)  x  3  =  26,460  cubic  feet  per  minute  as  the 
adequate  amount  of  ventilation.  While  the  allowance  of  air  for  men 
and  animals  is  absurdly  small  yet  a  large  part  of  the  air  which  is 
allowed  for  the  other  purposes  will  serve  for  their  consumption,  and 
hence  the  practical  outcome  of  this  estimate  would  be  probably  a  very 
good  one  if  the  mine  was  not  a  fiery  one. 

The  formula  given  by  Bagot  is  as  follows  : 

Q  =  quantity  of  air  in  cubic  feet  to  be  supplied  per  minute. 

M=  number  of  men  at  work  in  the  mine. 

H  —  number  of  horses  at  work  in  the  mine. 

P  =  pounds  off  gunpowder  fired  per  hour. 

O  —  tons  or  cubic  yards  of  coal  raised  per  minute. 

A  —  square  yards  of  area  of  surface  coal  exposed  to  the  ventilat- 
ing current. 

Then  Q—  24  M  +  72  H  -f  192  P  =  100  O  -\-  A. 

Thus,  in  a  mine  with  400  men,  30  horses,  output  of  600  tons  per 
day,  using  8  pounds  of  powder  per  hour,  and  having  a  coal  surface  of 
1,000  yards: 

Q    =     400   (24)     -f     30    (72)     -f-     8    (192)     :  :     17^    (loo)     -f     1,000    = 

16,062^4  cubic  feet  per  minute. 

This  formula  is  entirely  inadequate  even  for  a  mine  that  is  not 
fiery,  for  it  would  give  to  each  man  only  about  40  cubic  feet  per 
minute,  while  80  cubic  feet  per  minute  should  be  the  minimum  allow- 
ance per  man  in  a  metal  mine  and  100  cubic  feet  per  minute  in  a  coal 


292  FURNACE    VENTILATION. 

mine  producing  little  gas,  while  for  fiery  mines  it  is  necessary  to  pro- 
vide air  ways  and  fans  capable  of  increasing  this  quantity  from  three 
to  six  times  as  occasion  demands. 

As  the  mine  is  extended  and  becomes  deeper,  the  quantity  of  air  re- 
quired increases  if  the  number  of  men  and  the  output  remain  the  same, 
because  some  air  is  required  to  keep  those  parts  of  the  mine  which 
have  been  worked,  free  from  accumulations  of  gas  so  long  as  they  are 
not  entirely  abandoned  and  closed  off  from  the  working  part  of  the 
mine  by  a  close  and  continuous  wall.  The  quantity  of  air  required  in 
different  parts  of  a  coal  mine,  and  especially  of  a  fiery  mine,  varies 
from  day  to  day  and  must  be  adjusted  by  daily  observations  of  the 
proportion  of  fire  damp  present  made  by  skilled  men  each  morning 
before  the  workmen  go  in  for  work. 

Having  fixed  on  the  amount  of  air  to  be  supplied,  the  next  thing- 
is  to  settle  on  the  means  to  be  used  for  moving  the  air,  bearing  in 
mind  that  it  is  not  only  present  or  immediate  wants  that  are  to  be  pro- 
vided for,  but  that  as  the  mine  extends  the  amount  of  air  required 
will  become  greater,  and  the  friction  will  increase,  requiring  more 
force. 

To  secure  ventilation  in  a  mine  it  must  have  at  least  two  distinct 
openings,  each  communicating  with  the  outside  air.  If  now  the  air  in 
the  mine  becomes  lighter,  volume  for  volume,  than  the  superincumbent 
atmosphere,  by  becoming  heated — by  mixture  with  fire  damp — or,  by 
the  addition  of  vapor  of  water,  the  tendency  is  to  produce  a  current 
flowing  out  of  one  opening  and  into  the  other.  If  the  openings  are 
at  different  levels  the  current  will  enter  at  the  lower  opening  and  pass 
out  at  the  higher  one  in  winter,  while  the  reverse  would  occur  in  sum- 
mer, unless  the  temperature  of  the  mine  exceeds  that  of  the  external 
air.  The  current  thus  produced  will  be  usually  feeble,  and  it  would 
only  be  in  a  small  mine,  with  large  shafts  and  galleries,  and  few  work- 
men and  lights,  that  this  natural  ventilation  would  be  sufficient,  and  it 
will  necessarily  be  irregular  and  vary  with  the  season,  time  of  day 
etc.,  because  it  depends  mainly  on  difference  of  temperatures.  It  is 
especially  liable  to  be  defective  in  warm  weather. 

Artificial  means  of  ventilation  for  a  mine  consist  either  of  means 
of  heating  the  air  in  one  of  the  shafts,  or  of  some  form  of  fan  to  force 
the  air  to  move  in  a  particular  direction. 

The  heating  of  the  air  in  an  upcast  shaft,  by  means  of  a  furnace, 
has  been  and  still  is  extensively  employed  in  mine  ventilation,  but  in 
mines  giving  out  much  fire  damp  it  is  being  superseded  by  the  fan, 
and  in  such  mines  its  use  is  forbidden  by  the  Pennsylvania  law. 


FURNACE    VENTILATION.  293 

If  a  furnace  be  used  to  ventilate  a  fiery  mine,  special  precautions 
are  necessary  to  prevent  the  air  of  the  mine  from  coming  in  contact 
with  the  flame  of  the  furnace — and  for  this  purpose  it  may  even  be 
necessary  to  bring  the  air  required  to  support  combustion  through  a 
separate  channel  from  the  outer  air.  Where  there  is  no  fear  of  any 
explosive  mixture,  and  the  upcast  shaft  can  be  used  solely  for  venti- 
lation, the  air  of  the  mine  can  pass  directly  through  and  over  the  fur- 
nace, which  should  be  in  a  gallery  near  the  bottom  of  the  shaft,  or  in 
a  space  excavated  for  the  purpose. 

The  furnace  costs  less  than  the  fan  to  construct,  and  its  work  is 
not  so  liable  to  be  interrupted  for  repairs,  while  even  if  it  does  stop 
for  an  hour  or  two  the  heated  shaft  will  still  continue  to  act.  On  the 
other  hand,  it  consumes  much  more  fuel  than  would  be  required  to 
run  a  fan  to  do  the  same  work,  and  requires  large  passages,  since  it 
cannot  work  against  much  friction. 

Gallon  says  that  ''in  practice  it  is  usually  sufficient  to  raise  the 
temperature  of  the  air  that  has  passed  round  the  workings  from  20° 
to  40°  F.,  so  that  the  column  of  heated  air  in  the  upcast  has  not  a 
higher  temperature  than  100°  to  115°  F.  In  these  conditions  of  tem- 
perature the  upcast  shaft  may,  if  necessary,  be  used  even  as  a  winding 
pit,  provided  that  wire  ropes  are  employed  in  it.  It  ought  not  to  be 
made  use  of  for  pumping,  however,  because  a  pumping  shaft  is  always 
very  wet,  and  drops  of  water  falling  down  are  hurtful  to  the  ventila- 
tion, since  they  cool  the  ascending  air." 

According  to  Ramsay,  "  The  maximum  power  of  a  furnace  by 
rarifyingtheatr  appears  to  be  about  1,000  cubic  feet  per  minute  per  foot 
area  of  the  upcast  shaft,  with  a  density  of  between  2  and  3  inches  of 
water-gauge." 

Furnaces  are  used  chiefly  in  English  mines,  while  fans  are  preferred 
in  France,  Belgium  and  America.  Ventilating  fans  for  mines  may  be 
either  propelling  or  exhaust;  but  as  a  rule  the  exhaust  fans  are  used. 

Figure  58  is  a  copy  of  a  plate  given  in  the  work  of  Agricola,  pub- 
lished in  1556,  to  show  the  various  kind  of  fans  then  used  or  proposed 
for  mine  ventilation.  One  specimen  is  shown  with  a  square  case  and 
one  with  a  round  one. 

He  says  that  these  fans  may  be  driven  by  a  windmill,  but  as  there 
is  often  no  wind  these  are  less  useful  than  those  which  can  be  turned 
by  hand. 

Figure  59  shows  the  construction  of  some  of  these  fans. 

It  is  a  long  step  from  these  quaint  old  patterns  to  those  of  the 
present  day. 


294 


FAN    VENTILATION. 


FIG.  58. 

A,  circular-case  fan.    £,  square-case  fan.    C,   air  inlet.    E,  wooden  air  ducts.    H, 
weights  at  ends  or  rods  acting  like  a  fly-wheel. 


FANS. 


295 


The  fan  that  is  now  most  used  in  mine  ventilation  is  the  Guibal 
fan  with  various  modifications,  and  of  diameters  varying  from  15  to 
30  feet,  although  there  are  several  in  use  of  diameters  of  from  35  to 
50  feet.  It  is  difficult  to  obtain  reliable  data  as  to  the  efficiency  of 
different  forms  and  sizes  of  fans  used  in  mine  ventilation,  or  as  to 
their  relative  economy  in  working,  because  no  .two  mines  are  alike  in 


FIG.  59- 

A,  fan  made  of  boards.  .#,  one  having'  the  blades  made  of  overlapping  plates  of  thin 
wood.  C,  fans  made  with  goose  feathers.  Z>,  central  portion  of  shaft.  E*  axle.  F,  handle. 

the  amount  of  friction  presented  to  the  air  currents  which  traverse 
them,  and,  therefore,  in  the  amount  of  force  required  to  move  a  given 
quantity  of  air  through  them,  and  in  fact,  the  same  mine  will  differ  in 
this  respect  in  successive  months. 

The  best  collection  of  data  on  this  subject  which  we  have  seen  is 
contained  in  a  paper  by  R.  Van  A.  Norris,  of  Wilkesbarre,  Pa.,  on 
"  Centrifugal  Ventilators,"  read  before  the  American  Institute  of  Min- 
ing Engineers,  in  October,  1891.  From  this  it  appears  that  a  double 


296 


FANS. 


Guibal  fan,  20  feet  in  diameter  and  6  feet  wide,  running  at  TOO  revo- 
lutions per  minute,  removed  3,369  cubic  feet  of  air  per  revolution, 
working  against  a  resistance  equal  to  2^  inches  of  water  gauge,  and 
that  a  Guibal  fan,  35  feet  in  diameter  and  n'8"  wide,  at  46  revo- 
lutions per  minute,  removed  4,975  cubic  feet  per  minute  with  a  water 
gauge  of  1.95  inches. 

The  preference  appears  to  be  given  to  fans  of  from  iS  to  25  feet 
in  diameter.  Simplicity  and  strength  of  structure  in  a  fan  and  its 
connections,  so  as  to  do  away,  as  far  as  possible,  with  all  danger  of 
accidental  stoppage,  are  most  important,  for  in  a  fiery  mine  10  min- 
utes stoppage  of  the  fan  may  mean  death  to  the  miners. 


CP.QSS  SECTION  Of  VCUT1UATQR 

PIG.  60. 

Large  fans,  including  all  over  20  feet  in  diameter,  running  at  com- 
paratively low  speeds,  move  large  quantities  of  air  provided  the  supply 
comes  to  them  freely — that  is,  if  the  galleries  are  large  and  the  mano- 
metrical  depression  low,  but  lose  much  of  their  efficiency  if  they  have 
to  work  against  high  resistances.  In  this  last  case  some  form  of  blow- 
ing machine  in  which  a  definite  volume  of  air  is  taken  in  and  delivered 
in  a  given  time  at  a  given  speed,  irrespective  of  the  resistance,  may  be 
preferred,  since  the  increase  of  power  for  increase  of  resistance  can  be 
calculated  and  provided  for.  These  include  such  machines  as  Fabry's 
and  Lemielle's  ventilators  and  Root's  blower.  Figure  60  shows  a  cross- 
section  of  the  Root's  blower  used  at  the  Chilton  colliery,  Ferryhill,  Eng. 


AIR-WAYS.  297 

Each  of  the  rotary  pistons  is  25  feet  in  diameter  and  13  feet  wide, 
the  sides  being  covered  with  wood  and  the  ends  with  sheet  iron.  The 
calculated  capacity  is  5,800  cubic  feet  per  revolution. 

The  distribution  of  the  air  is  a  matter  of  great  importance  in  mine 
ventilation,  especially  in  coal  mines.  The  fresh  air  should  be  delivered 
with  as  little  loss  and  contamination  as  possible  at  the  face  of  the 
workings,  that  the  men  may  have  the  benefit  of  it  and  so  that  if  an 
explosion  does  take  place  it  shall  not  cutoff  their  air  space.  To  effect 
this  it  is  necessary  to  direct  the  incoming  current  of  air  to  follow  a 
given  course,  providing  a  separate  and  distinct  passage  for  it,  to 
divide  it  at  certain  points,  carrying  a  part  in  one  direction  and  a  part 
in  another  in  quantities  proportional  to  the  amount  required  at  the 
different  termini,  and  to  take  it  into  shafts  and  galleries  which  are  in 
process  of  construction  and  in  which,  therefore,  temporary  provision 
must  be  made  for  two  channels,  one  for  the  incoming  and  the  other 
for  the  outgoing  air.  This  isolation  of  the  currents  is  effected  by  the 
use  of  partitions  which  may  be  permanent  walls  of  the  natural  rock  left 
for  the  purpose,  or  walls  built  for  the  purpose,  or  wooden  or  cloth 
partitions,  or  special  air  ducts  of  wood  or  iron.  As  the  works  advance 
these  brattices  or  partitions  should  be  provided,  and  it  is  to  neglect  of 
this  until  the  air  at  the  face  of  the  work  becomes  so  foul  that  the 
brattice  becomes  an  absolute  necessity,  that  a  considerable  part  of  the 
ill  health  of  the  men  and  of  danger  from  fire  damp  is  due.  It  is  in  the 
adjustment  and  constant  supervision  of  these  partitions  to  meet  the 
changes  of  work  in  the  mine,  to  secure  the  separation  of  the  air  currents 
without  interfering  with  transport,  and  in  doing  this  with  the  least 
friction  and  resistance  to  the  movement  of  the  air,  that  the  knowledge 
and  practical  efficiency  of  the  engineer  or  superintendent  is  especially 
manifest.  It  must  be  constantly  borne  in  mind  that  the  larger  and 
more  direct  the  channels  through  which  the  air  moves  the  less  power 
is  required  to  move  it,  and  the  greater  therefore  is  the  efficiency  of  the 
fan  or  other  motive  power  employed  for  that  purpose.  The  galleries 
should  be  as  large  as  the  cost  of  their  construction  and  maintenance 
will  permit,  and  their  section  should  be  as  uniform  as  possible  to  avoid 
eddies.  The  return  air  ways  should  be  at  least  as  large  as  those  for 
supply,  and  it  is  better  that  they  should  be  larger  because  the  volume 
of  the  incoming  air  is  increased  by  leakage  of  gas  from  the  rock  and 
by  increase  of  temperature. 

Where  the  disposal  of  fire  damp  is  an  important  object,  the  fact 
that  this  gas  is  lighter  than  air  and  tends  to  rise  above  it  when  pure, 
makes  it  important  that  the  return-current  should  be  upward  and 


298 


FAN    VENTILATION. 


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HEAD    OF    AIR.  299 

never  downward  ;  in  other  words,  the  fresh  air  should  be  delivered  at 
the  lowest  part  of  the  workings. 

When  the  fire  damp  has  once  become  mixed  with  air  the  law  of 
the  diffusion  of  gases  prevents  their  separation  and  the  mixture  must 
move  as  such.  As  the  workings  get  lower,  what  was  at  first  a  fresh- 
air  gallery  may  become  a  return-air  passage. 

In  the  ventilation  of  large  mines  the  resistance  tQ  the  movement 
of  the  air  due  to  friction  of  surfaces  of  galleries,  and  to  eddies  pro- 
duced by  abrupt  turns  or  sudden  expansions  and  contractions  of  ducts 
is  often  very  great,  and  a  large  part  of  the  power  employed  to  pro- 
duce air  currents  is  needed  to  overcome  this  resistance. 

The  amount  of  friction  depends  on  the  size  and  length  of  the 
galleries,  the  number  and  character  of  the  angles  through  which  the 
current  must  turn,  and  on  the  velocity  of  the  current,  hence  it  is  not 
the  same  in  different  mines,  nor  in  the  same  mine  at  different  times, 
the  tendency  being  to  its  increase  with  the  increase  in  the  length  and 
depth  of  the  workings.  It  increases  in  direct  proportion  to  the  area 
of  rubbing  surface  and  as  the  square  of  the  velocity  of  the  current. 
The  average  co-efficient  of  friction  in  mines  is  given  by  Atkinson*  as 
being  0.0217  pound  per  square  foot  of  rubbing  surface  with  a  velocity 
of  the  air  current  of  1,000  feet  per  minute.  If  the  velocity  of  the 
current  is  only  i  foot  per  minute  the  co-efficient  of  friction  becomes 
0.0000000217  pound. 

For  any  given  gallery  the  formula  is  /  a  =  k  s  z'2,  in  which/  = 
pressure  per  square  foot  of  area,  a  =  sectional  area  in  square  feet, 
k  =  co-efficient  of  friction,  s  =  rubbing  surface,  and  v  =  velocity  of 
the  current  in  thousands  of  feet  per  minute,  1,000  feet  per  minute 
being  counted  as  i. 

In  mining  engineering  the  pressure  in  pounds  per  square  inch 
required  to  impart  a  given  velocity  to  a  column  of  air  is  often  called 
the  "head  of  air,"  because  in  using  furnaces  it  was  calculated  as  the 
difference  in  height  of  two  columns  of  air  of  equal  weight,  but  of 
different  temperatures.  The  total  resistance  to  the  flow  of  air  due  10 
friction,  eddies,  etc.,  in  any  given  system  of  air  circulation  may  be 
represented  as  the  resistance  which  would  be  given  by  an  orifice  of  a 
certain  size  in  a  thin  plate,  for  a  certain  head  of  air,  which  may  be 
called  the  resistance  of  the  mine.  If  the  head  of  air — or  briefly,  the 
head,  be  stated  as  the  number  of  foot  pounds  of  force  required  to 
drive  a  pound  of  air  through  a  given  orifice,  and  the  orifice  be  taken 

*A  practical  treatise  on  the  gases  met  with  in  coal  mines,  etc,  London, 
1889,  p.  37. 


300  HEAD    OF    AIR. 

as  having  the  area  k  a — a,  being  the  area  in  square  feet,  and  k  the 
co-efficient  of  contraction,  usually  taken  as  0.65,  then  the  volume 
of  air  in  cubic  feet  passing  is  equal  to  the  square  root  of  the  head 

V* 
divided  by  the  resistance  of  the  orifice,  or  H  =  — — -. 

The  friction,  and  the  power  required  to  overcome  it,  increases 
very  rapidly  as  the  velocity  of  the  currents  increase,  hence  they  should 
be  as  slow  as  is  compatible  with  furnishing  the  amount  of  air  required. 
They  should  not  anywhere  exceed  8  feet  per  second,  to  avoid  danger- 
ous dusts  and  bad  effect  on  lamps,  and  5  or  6  feet  per  second  is  much 
preferable.  But  with  reduced  velocities  larger  air  ways  are  needed 
and  none  of  the  fresh  air  must  be  wasted,  hence  an  important  feature 
in  the  practical  adjustment  of  the  ventilation  of  a  mine  is  the  division 
of  the  entering  current  of  air  in  such  a  way  as  to  send  different 
amounts  to  different  parts  of  the  mine  in  proportion  to  their  needs, 
and  diminish  friction  by  increasing  the  area  of  the  air  passages,  and 
thus  permitting  the  required  quantity  to  pass  at  a  lower  velocity.  In 
this  "  splitting  the  current,"  as  it  is  termed,  each  split  takes  fresh  air 
directly  from  the  main  inlet,  and  thus  delivers  air  which  has  not 
passed  through  other  workings. 

The  amount  of  air  passing  through  a  given  opening  or  gallery  is 
determined  by  anemometrical  measurements,  and  the  pressure  under 
which  it  is  moving  is  ascertained  by  a  form  of  manometer  known  as 
the  water  gauge. 

The  following  is  a  list  of  a  few  of  the  most  important  works  on 
mine  ventilation: 

1.  Appendix  "  B"  to  Report  of  the  Commissioners  appointed  to  Inquire  into 

the  Condition  of  All  Mines  in  Great  Britain.  466pp.,fol.  London:  1864. 
This  contains  valuable  data  on  the  air  of  mines  by  Drs.  Taylor,  Angus 
Smith  and  Bernays,  and  with  this  should  be  compared  those  given  in  a 
valuable  paper  on  the  air  of  coal  mines  by.  Mr.  Nasmyth,  published  in  the 
British  Medical  Journal  of  August  4,  1888,  p.  222. 

2.  Lectures  on  Mining.     By  J.  Gallon;  translated;  Vol.  II.,  Chapter XX.     8vo. 

London:  1881. 

3.  A  Treatise  on  Ventilating  and  Working  Collieries.     By  J.  A.  Ramsay,  M.  E. 

London:  Longmans  &  Co.,  1882,  pp.  41. 

4.  The   Principles   of  Colliery  Ventilation.     By  Alan    Bagot.     2d   ed.,    8vo. 

London:  1882. 

5.  A  Practical  Treatise  on  the  Gases  met  with  in  Coal  Mines  and  the  General 

Principles  of  Ventilation.     By  J.  A.  Atkinson.     i2mo.     London:  1889. 

6.  A  Treatise  on  Practical  and  Theoretical  Mine  Ventilation.     By  E.  B.  Wilson. 

4th  ed.     New  York:  1891. 


CHAPTER  XIV. 

VENTILATION  OF  HOSPITALS  AND  BARRACKS.  BARRACK  HOSPITALS. 
HOSPITALS  FOR  CONTAGIOUS  DISEASES.  BLEGDAMS  HOSPITAL. 
U.  S.  ARMY  HOSPITALS.  CAMBRIDGE  HOSPITAL.  HAZLETON 

HOSPITAL.  BARNES  HOSPITAL.  NEW  YORK  HOSPITAL.  JOHNS 
HOPKINS  HOSPITAL.  HAMBURG  HOSPITAL.  INSANE  ASYLUMS. 
BARRACKS. 

WE  now  come  to  the  consideration  of  a  class  of  buildings  in  which 
the  subject  of  ventilation  is  specially  important — namely, 
hospitals. 

The  necessity  of  providing  these  buildings  with  more  than  the  usual 
means  of  ventilation  has  long  been  recognized,  and  in  almost  every 
large  hospital  which  has  been  planned  or  built  during  the  present 
century  some  attempt  has  been  made  to  meet  this  demand.  Yet,  in 
spite  of  the  experience  thus  gained,  and  of  some  careful  studies  by 
physicians,  engineers  and  architects  as  to  the  relative  merits  of  various 
systems,  it  must  be  confessed  that  the  results  obtained  have  too  often 
been  unsatisfactory. 

The  bad  results  of  imperfect  ventilation,  or  of  an  impure  air  supply, 
are  more  strikingly  evident  in  hospitals  than  in  other  buildings,  owing 
in  part  to  their  continuous  cccupation,  in  part  to  the  lowered  vitality 
of  their  inmates,  who  are  specially  susceptible  to  insanitary  influences, 
and  in  part  to  the  presence  of  special  causes  of  disease  in  the  form  of 
germs  or  miasms.  The  great  difficulty  in  providing  a  constant  and 
sufficient  supply  of  pure  air  to  hospital  wards,  in  such  a  way  that  at 
all  hours  of  the  day  or  night,  at  all  seasons,  or  in  all  conditions  of  wind, 
they  shall  be  free  from  all  odor  and  comfortable  for  the  patients,  is  not 
so  much  a  want  of  knowledge  of  the  means  by  which  this  may  be 
effected  as  it  is  the  expense  which  must  be  incurred,  not  only  in  provid- 
ing the  necessary  construction  and  apparatus  for  heating  and  ventila- 
tion, but  also  to  keep  the  system  in  operation  after  it  has  been  provided. 
This  expense  is  almost  invariably  underestimated,  and  those  who  have 
to  furnish  the  funds  for  the  support  of  the  institution  are  disappointed 


302 


PEST    HOUSES. 


accordingly,  and  in  attempting  to  reduce  the  cost  are  too  apt  to  reduce 
the  ventilation  also. 

The  hospitals  for  which  an  architect  is  liable  to  be  called  on  to 
prepare  plans  differ  greatly  in  purpose,  size  and  arrangement.  Among 
' he  simplest  are  those  intended  for  the  reception  of  contagious  dis- 
eases, the  so-called  pest  houses.  These  are  usually  cheap  temporary 


FIG.  61.— CROSS  SECTION,  ST.  PETERSBURGH  CITY  HOSPITAL. 

structures,  hastily  erected  to  meet  an  emergency,  and  the  architect  is 
rarely  consulted  with  regard  to  them.  It  would  be  much  better  if  he 
were,  for  such  hospitals  should  be  considered  as  an  indispensable  part 
of  the  municipal  machinery  of  every  city  of  10,000  inhabitants  and 
upward  ;  they  should  be  carefully  constructed  while  the  emergency  is 
vet  afar  off,  and  while  they  should  be  simple  and  cheap,  they  should 


BARRACK    HOSPITALS. 


303 


have  a  neat  and  attractive  appearance,  instead  of  looking,  as  they 
usually  do,  like  enlarged  dog  kennels.  Their  ugly, box-like  appearance 
can  be  done  away  with  by  a  simple,  broken,  cottage-like  outline,  with- 
out much  additional  expense,  and  they  will  then  be  considered  as 
worth  taking  care  of.  They  will  be  one-story  wooden  buildings, 
with  wards  containing  about  six  beds,  heated  by  a  stove  in  the  center. 


6(5)2 


FIG.  62.— FLOOR  PLAN  OF  ST.  PETERSBURGH  CITY  HOSPITAL. 


i.— Porch. 

2.— Hall. 

3. —  Nurses'  room. 

4.— Ward  kitchen. 


5. — Room  for  two  patients. 

6.— Bath. 

7._Ward. 


8.— Room  for  two  patients. 

g.-Hall. 
10. — Wash-room. 
1 1. — Water-closet. 


Through  or  around  this  stove  the  greater  part  of  the  fresh  air  should 
be  introduced  in  cold  weather,  while  the  foul  air  should  be  removed 
by  a  shaft  reaching  nearly  to  the  floor  near  the  stove,  and  containing 
the  stove-pipe  in  its  upper  part.  Upon  a  larger  scale  this  kind  of 
building  is  known  as  a  barrack  hospital,  and  excellent  results  have  been 
obtained  from  it.  To  illustrate  its  possibilities,  I  give  figures  showing 


FIG.  63.— CELLAR  PLAN  OF    ST.   PETERSBURGH  CITY  HOSPITAL. 


i.— Cellar. 
2.— Soil  pipes. 


3. — Foundation  of  stone.       5. — Foul-air  tubes  beneath  the  floor. 
6,  7.— Vessels  for  excreta. 


plan  and  cross  section  of  one  of  the  barracks  of  the  Roschdestwensky 
City  Hospital,  in  St.  Petersburgh  (Figs.  61  and  62). 

This  hospital  has  three  of  these  barracks,  constructed  in  1871-72, 
and  they  have  proved  to  be  a  great  success,  being  comfortably  warm 
in  the  extreme  cold  of  the  Russian  winter,  and  giving  excellent  results 
in  cases  of  typhus  and  jilso  in  surgical  cases. 


304  SMALL-POX    HOSPITALS. 

The  walls  of  this  barrack  are  triple,  inclosing  two  air  spaces.  The 
arrangement  of  the  ward  heating  and  ventilation  is  sufficiently  shown 
in  the  figures.  The  great  central  German  porcelain  stove  is  14  feet 
long,  4  feet  8  inches  wide,  and  6  feet  high.  This  so-called  stove  is 
rather  a  furnace,  fired  from  below,  and  has  through  it  eight  openings 
for  the  admission  of  fresh  warm  air  into  the  ward.  The  foul-air  flues 
open  into  the  central  smoke  flue,  as  shown  in  the  cross  section. 
Besides  this  central  stove,  there  are  three  others,  and  the  whole  fur- 
nish about  103,000  cubic  feet  of  fresh  air  per  hour.  When  the  ex- 
ternal temperature  is  not  below  the  freezing  point  these  stoves  are 
fired  but  once  a  day.  When  between  zero  and  32°  F.,  they  are  fired 
twice  a  day,  and  when  below  zero,  three,  and  in  extreme  cold,  four 
times  a  day.  When  I  was  in  this  ward  in  August,  1881,  it  was  quite 
free  from  unpleasant  odor,  although  it  was  filled  with  fever  cases;  the 
day  was  cold  and  raw,  but  the  temperature  of  the  ward  was  all  that 
could  be  desired.  It  is  an  interesting  hospital,  as  proving  that  even  in 
the  coldest  climates  such  wards  can  be  made  perfectly  comfortable  and 
at  the  same  time  be  kept  well  ventilated. 

An  interesting  form  of  hospital  ward  for  small-pox  patients  is 
shown  in  Figs.  64  to  67,  which  are  prepared  from  illustrations  pub- 
lished in  The  Builder.  This  hospital,  recently  constructed  by  the 
Corporation  of  Bradford,  England,  consists  of  two  wards  each  75x15 
feet,  placed  back  to  back  with  a  space  of  about  3  feet  between  them, 
forming  a  foul-air  chamber  from  which  the  air  is  drawn  by -an  aspirat- 
ing shaft,  and  containing  below  a  fresh-air  chamber  and  heating  sur- 
faces. The  windows  are  tight  and  the  fresh  air  enters  through  the 
inlets  A  A  A  into  the  lowest  compartment  G,  of  the  space  between 
the  wards.  From  this  duct  the  air  passes  through  flues  J3,  and  enters 
the  ward  through  floor  gratings  at  the  foot  of  each  bed.  The  foul-air 
registers  are  in  the  ceiling  over  each  bed.  All  the  foul  air  must  pass 
through  the  furnace  at  the  base  of  the  aspirating  shaft.  For  the  Eng- 
lish climate  this  will,  no  doubt,  answer,  but  when  the  external  air  is  at 
zero  this  is  a  very  wasteful  method  of  heating. 

This  plan  of  subjecting  all  the  air  escaping  from  a  small-pox 
ward  to  high  temperature  is  in  accordance  with  a  plan  prepared 
several  years  ago  by  Dr.  Burdon  Sanderson,  who  proposed  that 
each  ward  should  be  in  the  form  of  a  ring,  with  the  chamber  from 
which  the  air  is  directly  extracted  in  the  center  of  the  ring,  and 
that  for  a  ward  of  12  beds,  having  a  capacity  of  about  1,200  cubic 
feet  per  bed,  the  removal  of  air  should  be  about  120,000  cubic  feet  per 
hour. 


SMALL-POX    HOSPITALS. 


305 


"  The  beds  would  be  arranged  as  near  as  possible  to  and  imme- 
diately below  each  extracting  opening,  and  would  be  placed  against 
the  internal  wall,  and  each  bed  would  be  placed  between  two  of  the 
septa  or  screens  which  pass  to  a  certain  distance  out  from  the  internal 
wall  into  the  annular  space,  so  that  the  head  of  each  bed  would  be  in- 


FlG.  64. 


FIG.  65. 


LJ-J-JL 
jTTpftjfT 


LH 


FIG.  66. 


FIG.  67. 

eluded  in  the  space  between  each  two  neighboring  septa.  The  space 
within  the  ring  communicates  with  the  annular  space  by  extracting 
openings,  and  discharges  the  air  into  a  chamber,  where  it  could  be 
subjected  to  a  higher  temperature,  so  as  to  destroy  all  organic  matter  it 
might  contain." 


306 


SMALL-POX    HOSPITALS. 


The  windows  are  not  to  open.  Twenty-four  openings  for  fresh  air 
are  to  be  made  in  the  external  wall,  each  having  2  square  feet  of  area. 
The  movement  of  air  through  the  outlet  openings  is  intended  to  be  at 


SECTION 


.£?  ~A0 


SCALE  OF  FEET 

FIG.  68. 


the  rate  of  i  mile  per  hour,  allowing  10,000  cubic  feet  of  air  for  each 
patient,  and  to  secure  this  slow  movement  and  thus  prevent  draughts, 
the  outlet  openings  are  also  to  be  2  feet  square.  The  method  of 


SMALL-POX    HOSPITALS. 


307 


warming  proposed  is  to  carry  around  hot-water  pipes  in  front  of  the 
inlet  openings.  From  the  fan  the  air  is  to  pass  to  a  gas  furnace,  prob- 
ably in  the  roof  of  the  house. 

From  this  description  and  the  plans,  of  which  copies  are  appended, 
it  is  evident  that  while  it  is  theoretically  possible  to  thus  disinfect  all 
the  air  passing  through  a  small-pox  ward,  it  would  be  at  a  relatively 
great  expense.  The  circular  ward  is  used  in  the  new  City  Hospital  at 
Antwerp,  and  the  same  principle  is  employed  in  the  Octagon  Ward  of 
the  Johns  Hopkins  Hospital,  at  Baltimore  ;  but  in  both  these  the  beds 
are  arranged  against  the  outer  wall,  having  the  heads  toward  the  win- 
dows, which  is  a  much  more  convenient  way  of  arranging  them  than  in 
the  plan  above  proposed,  both  because  it  allows  more  space  about  each 


FIG.  6g. 

2. — Furnace.  4. — Heaters.  6. — Fresh-air  duct  to  air  .chamber. 

3.— Fresh-air  chamber.      5.— Fresh-air  duct  from  air        7.— Fresh  air  inlets, 
chamber. 

a — Fresh-air  inlet.  c — Point  of  entrance  of  foul-air  duct  to  aspirating 

b— Foul-air  duct.  chimnev. 


bed  and  because  it  does  not  compel  the  patients  to  face  the  light,  which 
would  be  extremely  unpleasant  in  the  acute  stage  of  small-pox. 

A  second  objection  is  that  the  central  shaft  is  unnecessarily  large, 
as  are  also  the  inlets  into  it.  It  is  not  desirable  to  reduce  the  velocity 
of  the  air  at  the  outlets  or  in  foul-air  ducts  below  4  or  5  feet  per 
second,  because  at  very  low  velocities  a  very  slight  thing  will  disturb 
the  currents.  The  velocity  at  the  outlet  has  comparatively  little  to  do 
with  the  production  of  draughts. 

These  suggestions  are  made,  not  for  the  purpose  of  fault-finding, 
but  because  everything  which  comes  from  such  distinguished  authority 
should  be  made  as  perfect  as  possible. 


3o8 


ISOLATING    WARDS. 


It  seems  probable,  however,  that  the  neighborhood  would  be  more 
certainly  and  economically  protected  by  the  continuous  enforcement 
of  vaccination  than  it  would  be  by  any  particular  form  of  hospital. 

Another  arrangement  of  a  ward  for  infectious  diseases  is  shown 
in  Figs.  69,  70  and  71,  which  give  the  basement  and  floor  plans, 
.nd  longitudinal  section  of  such  a  ward  in  the  Blegdams  Hospital, 
n  Copenhagen. 

If  an  isolating  ward  is  to  receive  several  different  kinds  of  con- 
tagious or  offensive  disease  it  must  be  divided  into  as  many  distinct 
divisions,  each  having  entirely  separate  ventilation.  In  the  isolating 

9  9 


-JLl— 


L— Ward. 

2. — Isolation  ward. 

3.— Nurse. 

4. — Kitchen. 

5. — Bath-room. 

6.— Water-closet. 

7.— Corridor. 

8. — Lobby. 


FIG.  70. 

a — Inlet  openings  for  fresh  air. 

b — Aspirating  openings  for  vitiated  air. 

c — Chimney. 

Z?— Wash-stand. 

Y—  Sink 

^"-Interceptor. 

X— Sewer. 


ward  of  the  Johns  Hopkins  Hospital  there  are  rooms  on  either  side  of 
a  central  corridor,  which  corridor  is  freely  open  to  the  outer  air.  Each 
room  has  an  open  fireplace  with  a  separace  flue,  placed  in  the  center  of 
the  inner  wall  of  the  room.  On  one  side  of  this  chimney  is  the  entrance 
to  the  room  from  the  corridor,  closed  by  double  doors;  on  the  other 
side  is  a  small  closet  containing  a  commode,  the  chamber  from  which 
can  be  removed  through  an  opening  in  the  wall  without  entering  the 
room.  This  closet  is  lined  with  galvanized  iron  and  has  a  separate 
exit  flue  in  which  is  an  accelerating  steam  coil.  The  door  of  this  closet 
does  not  come  to  the  floor  by  4  inches  and  the  exit  of  the  air,  which 
enters  the  room  through  large  openings  in  the  outer  wall,  is  mainly 


ISOLATING    WARDS. 


3°9 


through  this  closet  and  up  its  special  flue  which  is  of  iron  so  that  the 
whole  can  readily  be  cleansed  with  flame. 

A  longitudinal  section  of  this  ward  is  shown  in  Fig.  72,  a  longi- 
tudinal section  of  the  inner  wall  of  one  of  the  rooms  is  shown  in  Fig. 


i. — Chimney. 

a.— Furnace. 

3.— Fresh-air  chamber. 

4.-Heater. 

5.— Fresh-air  duct 

6.— Ward. 


FIG. 


a — Inlet  openings  for  fresh  air. 

b— Aspirating  openings  for  y,itiated  air. 

c— Inlet  of  aspirating  duct  in  chimney. 

d— Outlet  opening  in  chimney  for  vitiated  air  from  closets. 

e— Inlet  opening  for  fresh  air  in  air  chamber. 


FIG.  72. 


73  and  a  transverse  section  through  the  ventilating  closet  in  Fig.  74. 
The  plan  of  fireplace  and  commode  is  shown  in  Fig.  75.  Three  of  the 
rooms  are  larger  than  the  rest,  and  in  these  the  fresh  air  enters  through 
the  floor,  which  for  a  distance  of  7  feet  from  the  outer  wall  is  perfor- 


3io 


ISOLATING    WARDS. 


ated  with  %-inch  holes,  there  being  5,000  such  holes  in  each  room 
The  heaters  for  these  rooms  are  marked  H  C  in  Fig.  72,  and  are 
shown  on  a  larger  scale  in  Fig.  76. 


WARO 


FIG.  73. 


FIG.  74. 


FIG. 


FIG.  76. 


ARMY    HOSPITALS. 


312 


ARMY    HOSPITALS. 


FIG.  78. 


ARMY    HOSPITALS. 


313 


FIG.  79. 


314 


ARMY    HOSPITALS. 


FIG.  80. 


ARMY    HOSPITALS. 


315 


Figures  77  and  78  show  the  basement  and  floor  plans  of  a  small 
U.  S.  Army  hospital,  containing  eight  beds  in  the  ward  and  heated  by 
steam,  with  indirect  radiation  for  the  ward  and  direct  radiators  in 
other  rooms. 

The  boiler  for  this  plant  is  6  feet  long  and  30  inches  in  diameter, 
with  twenty-three  2^ -inch  tubes.  The  indirect  radiators  are  in  galva- 


FIG.  81. 


nized-iron  chambers  and  are  supported  on  iron  bars.  There  are  two 
outlet  flues  for  the  ward,  leading  to  vertical  shafts,  as  shown  in  Fig. 
78.  The  amount  of  radiating  surface  is  indicated  for  a  temperature 
of  20°  F. ;  it  must  be  increased  where  the  minimum  temperature  falls 
below  this. 


3(6 


CAMBRIDGE    HOSPITAL. 


Figures  79  and  80  show  basement  and  first-floor  plans  of  a  U. 
S.  Army  Post  hospital  of  from  24  to  48  beds,  depending  upon  the 
length  of  the  wings,  and  intended  for  cold  climates.  The  heating  is  by 
direct-indirect  radiation  in  the  wards,  by  direct  radiation  in  other 
rooms.  The  location  and  dimensions  of  boiler  and  steam  floor  mains 
are  given  in  Fig.  79. 


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-V  I       rH 


k    =-  ayU| 
ff        iinill 


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f/lf/Jf e."  B"AJ/V>V«.    \f>n,H,~-r~c^'W~p  *,*'•&  c, 

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FIG.  82. 

Figure  8 1  is  a  plan  of  a  part  of  the  basement,  and  Fig.  82  a  plan 
of  the  corresponding  portions  of  the  first  and  second  floors  of  the 
Cambridge  Hospital,  Cambridge,  Mass. 

The  wards  are  connected  with  the  administration  building  by  roofed 
corridors.  The  sides  of  these  are  glazed,  but  in  such  a  manner  that 
the  frames  can  be  removed  in  fine  weather.  The  upper  stories  of  the 
administration  building  are  to  be  used  as  private  wards. 


CAMBRIDGE    HOSPITAL.  317 

The  main  room  of  each  pavilion  is  30'  4"  x6o'  6"  ;  the  floor  space 
to  each  bed  being  115  square  feet,  and  the  cubical  air  space  about 
1,840  feet. 

The  sun-rooms  at  the  ends  of  the  pavilions  are  8x30  feet,  with 
hammered  glass  roofs  and  clear  glazed  sides  extending  almost  to  the 
floor.  The  level  of  the  sun-room  floor  is  very  slightly  below  the  floor  of 
the  principal  ward,  just  enough  to  shed  water  outward,  but  not  sufficie:  i 
to  interfere  with  the  movements  of  an  invalid's  chair.  The  sun-roorn 
is  on  the  south  end  of  the  wards,  and  the  position  of  the  pavilions  be- 
ing north  and  south,  sunlight  is  available  during  the  whole  day. 

The  administration  building  is  warmed  by  direct  radiation,  sup- 
plemented by  indirect  radiation  in  the  main  hall,  and  all  sick  rooms  or 
chambers  have  an  open  fireplace.  The  pavilions  are  warmed  ry  in- 
direct radiation,  supplemented  by  direct  radiation  in  the  sun-i.ooms, 
halls  and  bath-rooms. 

The  warming  apparatus  is  arranged  to  be  worked  either  as  a  low- 
pressure  steam,  or  as  a  hot-water  apparatus.  Two  boilers  are  used, 
located  in  the  cellar  of  the  administration  building,  14  feet  long  by  42 
inches  in  diameter,  each  containing  60  2^-inch  tubes.  These  boilers 
are  connected  with  a  2i-inch  vertical  cast-iron  smoke-pipe  located 
within  the  aspirating  shaft  A  S,  cellar  plan.  Steam  or  hot  water,  as 
the  case  may  be,  is  carried  to  the  pavilions  by  the  4-inch  pipes  shown, 
where  it  is  distributed  to  the  indirect  heaters,  which  are  "  pin  "  sec- 
tions, center  connection,  eight  sections  being  used  to  each  hot-air  box. 

Figure  83  is  a  section  and  Fig.  84  a  perspective  elevation  of  one 
of  these  air  boxes  showing  the  arrangement  of  the  air-inlet  pipes  A, 
mixing  valve  Z>,  hot-air  pipe  ff,  and  register  box  R,  within  the  wards, 
as  well  as  a  section  of  the  vent  ducts  V  A,  with  the  vent  outlet  under 
each  bed  (V). 

.The  coil  casings  or  air  boxes  are  made  of  No.  22  galvanized  iron, 
with  flanged  corners,  and  the  steam  radiator  is  suspended  midway  in 
the  case.  The  cold  air  enters  through  the  lo-inch  round  pipe  A^  Fig. 
84,  and  shown  separated  on  cellar  plan  by  the  arrows,  the  mouth  of 
which  is  protected  by  a  register  face  and  frame.  As  the  air  enters 
through  A,  it  can  be  made  to  pass  either  under  and  through  or  above 
the  heating  surfaces  of  the  radiator  by  means  of  a  sliding  damper  D, 
or  the  air  current  may  be  divided  by  placing  the  damper  in  a  nearly 
central  position,  allowing  some  of  the  air  to  pass  each  way,  thereby 
regulating  its  temperature  without  reducing  its  volume.  The  upper 
end  of  this  damper  is  connected  by  a  chain  with  a  pull-and-stop 
mechanism  within  the  ward,  so  that  the  attendant  can  regulate  the  heat 


3i8 


CAMBRIDGE    HOSPITAL. 


of  the  air  without  leaving  the  room.     The  registers  are  in  every  case 
underneath  the  windows  between  the  piers. 

The  vent  ducts  shown  on  cellar  plan  are  made  of  pine  lined  with 
zinc.     They  commence   16   inches  square  and  increase  to  22   inches 


FIG.  83. 


FIG.  84. 

square  for  each  side  of  each  ward  and  then  connect  into  a  main  duct 
36x27  inches,  their  position  being  against  the  ceiling.  At  ,5",  cellar 
plan,  the  main  ducts  from  each  pavilion  enter  a  short  down-shaft,  that 
they  may  connect  with  the  aspirating  shaft  below  the  floor  to  avoid 


MCCOSH    INFIRMARY.  319 

destroying  the  head  room  at  the  stairs.  From  the  points  marked  D  D 
on  the  ducts  near  the  middle  of  wards,  the  vent  duct  (V A)  is  divided 
by  a  midriff  in  a  horizontal  plane.  The  object  of  this  is  to  increase 
the  certainty  of  all  the  vent  openings  under  the  beds  drawing  alike. 
At  D  D,  also,  are  shown  branch  ducts  entering  stacks  in  the  middle  of 
the  large  wards.  Thfl^e  stacks  are  to  be  used  to  exhaust  the  ducts  in 
times  when  no  heat  is  in  the  main  aspirator  or  to  be  used  as  auxiliary 
to  it. 

Provision  is  made  for  a  stove  at  the  foot  of  each  stack  and  fire- 
places in  the  pavilion  wards  also  open  into  it.  The  latter  are  intended 
for  damp  weather  in  summer,  etc. 

At  S  S,  in  the  sun  rooms,  coils  of  pipe  are  run  under  the  windows 
for  extra  warmth. 

The  ventilation  of  this  hospital  was  designed  by  Dr.  Morrill 
Wyman,  and  has  proved  very  satisfactory.  Dr.  Wyman  informs  me 
that  the  heating  is  hardly  sufficient  in  very  cold  weather,  when  hot 
water  is  used,  the  mains  being  too  small,  but  steam  has  not  been  used 
for  several  years  owing  to  the  extra  labor  required  in  maintaining  fires. 

Figure  85  shows  the  basement  plan  of  the  Isabella  McCosh  In- 
firmary at  Princeton,  N.  J.,  a  small  hospital  for  the  benefit  of  sick 
students.  Figures  86  and  87  are  plans  of  the  first  and  second 
floors. 

The  ventilation  is  by  open  fireplaces.  The  infirmary  is  heated  by 
steam,  and  the  number  of  feet  of  heating  surface  required  in  each  room 
is  marked  on  the  radiator  stacks  shown  on  the  basement  plan.  Each 
set  ot  radiators  receives  its  fresh-air  supply  directly  from  the  outside 
air,  and  by  means  of  a  mixing  valve  operated  from  each  room.  «The 
temperature  of  the  incoming  air  is  regulated  to  suit  the  requirements 
without  diminishing  its  flow.  Every  heat  flue  has  its  separate  set  of 
radiators,  fresh-air  supply  and  mixing  valve,  and  can  be  operated  en- 
tirely independently  of  any  other  heat  flue. 

The  basement  plan  shows  by  a  light  line  parallel  to  the  wall  the 
surface  of  the  inside  finish,  which  is  the  same  for  the  other  stories,  but 
is  not  indicated  on  the  plans.  The  significance  of  the  reference  letters 
is  as  follows  :  A  and  B,  radiator  stacks,  serving  first  and  second 
stories,  respectively  ;  C,  ash  pit ;  D,  living  room  ;  £,  bedroom  ;  F  is 
a  coal  vault  in  the  basement  and  a  kitchen  on  the  upper  floors  ;  G, 
coal  vault ;  H9  boiler-room  ;  /,  a  double  "  Florida"  boiler  No.  66  ;  J, 
pantry  ;  K,  cellar  ;  Z,  dining-room  ;  M,  porch  ;  JV,  ward  ;  O,  heat 
flue  ;  P,  private  room  ;  Q,  linen  room  ;  ^,  steam  pipe  riser;  S,  nurses' 
room  ;  T,  halt  ;  £/,  portable  bath-tub  ;  V,  fixed  bath-tub  ;  W,  light 


320 


MCCOSH    INFIRMARY. 


well  ;    X,   direct  radiator  ;     Y,  sun   parlor ;    Z,  operating  room;    6°, 
apothecary's  room. 

Figure  88  is  a  vertical  section  through  one  of  the  first-floor 
radiator  cases  A.  External  cold  air  enters  through  the  copper 
wire  screen  C  over  an  aperture  in  the  basement  wall  W,  and  when 


dampers  are  in  a  certain  position,  passes  through  cold-air  cham- 
ber E  and  a  perforated  tin  plate  G  to  the  radiator  box  _/%  which  con- 
tains a  Gold's  pin  radiator  (not  here  shown),  and  thence  rises  to  the  hot 
chamber  //,  and  is  delivered  through  the  flue  /  and  the  register  J,  to 
the  first-floor  room.  K  is  a  clean-out  door,  and  D  is  a  damper  com- 
mander by  the  vertical  axis  and  handle  Z,  to  regulate  the  amount  of 


McCOSH    INFIRMARY. 


32I 


FIG.  86. 


322 


MCCOSH    INFIRMARY. 


Fio.  87. 


MCCOSH     INFIRMARY. 


323 


cold  air  admitted.  It  is  here  shown  wide  open.  The  mixing  valve  M 
is  here  shown  wide  open  for  hot  air.  It  is  operated  by  the  rod  N  and 
crank  jP,  commanded  by  the  lever  handle  O,  which  may  be  fixed  at 
any  position  on  its  segment  Q  by  a  set  screw.  The  valve  M  may  be 


FIG.  88. 


FIG.  89. 


324 


HAZLETON    HOSPITAL. 


revolved  about  its  horizontal  axis,  as  indicated  by  the  dotted  lines,  so 
as  to  admit  all  cold  air  direct  from  the  inlet  C,  or  any  desired  propor- 
tion of  hot  and  cold  air,  always  admitting  the  same  total  volume  of 
fresh  air,  whatever  its  position. 

Figure  89  is  a  sectional  perspective  of  the  radiator  case.  Figure 
90  is  a  plan  at  Y  Y,  and  Fig.  91  is  a  plan  at  X  X.  In  Figs.  90 
and  91  parts  of  two  radiator  cases  are  shown,  each  symmetrical  about 
its  center  line.  They  differ  only  in  that  S  is  26  inches  wide  made 
to  clear  window  R,  and  T  is  a  wider  one,  obscuring  the  window.* 


FIG.  90. 


FIG.  91. 


Figure  92  is  a  plan  of  the  basement  of  the  Miners'  Hospital 
at  Hazleton,  Pa.  The  fresh  air  is  furnished  by  a  propelling  fan 
4  feet  6  inches  in  diameter  located  at  F,  which  forces  it  through  a 
radiator  chamber  and  thence  through  the  outlined  ducts.  The  ducts 
indicated  in  solid  black  are  for  foul  air,  and  lead  to  an  exhaust  fan, 
also  4  feet  6  inches  in  diameter,  located  at  F\  where  it  discharges  into 
a  chimney.  Figure  93  is  a  plan  of  the  main  floor  showing  the  posi- 
tion of  the  foul-air  outlets  in  the  floor  of  the  wards.  The  system  is 
intended  to  change  the  air  in  the  wards  four  times  an  hour.  The 
building  contains  159,927  cubic  feet,  and  the  heat  and  power  are 
furnished  by  two  connected  30  horse-power  horizontal  tubular  boilers.f 

Of  all  small  hospitals  in  this  country  with  which  I  am  acquainted, 
the  one  in  which  the  heating  and  ventilation  has  been  most  thoroughly 
proved  to  be  satisfactory  is  the  Barnes  Hospital,  at  the  Old  Soldiers' 

*  From  The  Engineering  Record,  June  n,  1892. 
f  From  The  Engineering  Record,  January  18,  1890. 


HAZLETON    HOSPITAL. 


325 


326 


HAZLETON    HOSPITAL. 


FIG  93. 


BARNES    HOSPITAL. 


327 


Home,  near  Washington,  the  general  arrangement  of  which  is  shown 
in  Figs.  94  and  95. 

This  hospital  is  built  of  brick,  and  consists  of  a  central  adminis- 
tration building  measuring  52x55  feet,  two  pavilion  wings  each  64x29 
feet,  and  two  end  towers  each  24x46  feet.  The  central  building  has 
a  basement,  three  stories  and  a  mansard  roof,  the  rest  of  the  structure 
two  stories,  with  basement  and  mansard. 

The  total  amount  of  cubic  space  to  be  heated  is  about  310,000 
cubic  feet.  The  basement  is  occupied  by  the  heating  apparatus,  which 
is  hot  water,  and  consists  of  two  tubular  boilers,  each  9  feet  long  and 
42  inches  in  diameter,  with  mains,  pipes  and  coils.  The  heating  coils 
are  of  cast-iron  pipe,  3  inches  in  diameter,  and  are  placed  in  fresh-air 


FIG.  94.— BARNES  HOSPITAL,   PLAN  OF  BASEMENT,  WITH  FRESH- 
AIR  DUCTS  AND  HEATING  APPARATUS. 


chambers  in  the  basement,  as  shown  in  the  plan.  At  the  point  of  en- 
trance of  the  supply  pipe  to  each  coil  is  a  valve,  by  which  the  flow  of 
hot  water  may  be  diminished  to  any  degree,  and  the  temperature  of 
the  coil  regulated  accordingly. 

The  fresh-air  flues  are  of  terra-cotta  pipe,  built  into  the  walls  and 
opening  into  the  space  above  the  heating  coils. 

The  apparatus  has  maintained  a  uniform  temperature  of  about  70° 
F.  in  the  coldest  weather,  and  the  temperature  can  be  varied  at  the 
different  registers  to  suit  the  feelings  of  patients  near  them. 

When  the  natural  ventilation  by  open  windows  is  insufficient  or 
impracticable,  fresh  air  is  supplied  by  a  shaft  8  feet  in  diameter  and 
38  feet  high,  placed  74  feet  west  of  the  building.  This  shaft  is  con- 


328  BARNES    HOSPITAL. 

nected  with  a  brick  air  duct,  286  feet  long,  which  passes  beneath  the 
basement  through  its  entire  length,  and  gives  off  branches  leading  to 
the  air  chambers  containing  the  heating  coils. 

At  the  point  of  junction  of  the  vertical  shaft  with  the  fresh-air 
duct  is  located  the  fan,  which  is  8  feet  in  diameter  and  has  24  blades, 
each  12  inches  wide. 

The  motive  power  for  this  fan  is  furnished  by  a  six  horse-power 
engine,  and  the  amount  of  coal  required  to  run  it  is  about  140  pounds 
for  24  hours.  The  fan  is  usually  run  at  60  revolutions  per  minute, 
giving  a  velocity  in  the  air  duct  of  from  400  to  600  feet  per  minute, 
the  cross-section  of  the  duct  at  its  throat  being  40  feet  square.  The 
removal  of  foul  air  by  aspiration  is  affected  by  two  chimneys  in  the 
administration  building.  Each  chimney  measures  4/4//x5'8'/,  and  is 
96  feet  high. 

A  boiler-iron  flue,  2  feet  in  diameter,  is  placed  in  the  center  of 
each  chimney,  extending  from  the  basement  to  a  height  of  3  feet  above 
the  chimney  cap  ;  into  these  flues  pass  all  the  products  of  combustion 
from  the  hot-watef  and  steam-boiler  furnaces,  as  well  as  those  from 
the  kitchen  range.  Each  flue  has  a  basket  grate  at  its  base,  in  which 
a  fire  can  be  built  when  the  furnaces  are  not  acting. 

Into  the  chimney  shafts  outside  these  flues  empty  the  foul-air 
ducts  from  the  wards.  These  ducts  are  3  feet  3  inches  wide,  i  foot 
deep  and  50  feet  long,  and  are  placed  above  and  below  the  center  of 
each  ward  with  which  they  communicate  by  accurately  closing  regis- 
ters placed  in  .the  center  of  the  floor  and  ceiling.  These  foul-air  boxes 
are  lined  with  tin  and  are  cleaned  daily. 

Each  ward  contains  12  beds,  is  50'  x  24'  x  15',  and  has  five  foul- 
air  registers  along  the  center  line  of  the  floor,  and  five  in  the  ceiling. 

Each  of  the  upper  registers  has  a  clear  area  of  1.33  square  feet  of 
opening,  and  each  lower  register  1.5  square  feet  of  clear  opening.  Each 
lower  ward  has  16  fresh-air  inlets,  eight  being  10  inches  above  the 
floor  and  eight  10  inches  below  the  ceiling ;  in  the  upper  wards  the 
upper  registers  are  omitted.  Each  fresh-air  register  has  a  clear  area 
of  i  square  foot. 

The  double  set  of  inlets  in  the  lower  wards  was  arranged  for  ex- 
perimental purposes  to  test  the  value  of  General  Morin's  theory  that 
the  warm  air  should  be  introduced  at  the  ceiling.  It  was  found  that 
when  this  was  done  there  was  a  difference  of  10  degrees  in  the  tem- 
perature between  the  floor  and  the  ceiling,  and  that  the  patients  com- 
plained of  cold  feet  and  discomfort.  It  is  also  evident  that  when  the 
warm  air  is  introduced  near  the  ceiling  it  is  impossible  to  vary  the  tern- 


BARNES    HOSPITAL. 


329 


FIG.  95.- HOSPITAL  AT  SOLDIERS'  HOME,  WASHINGTON,  D.  C. 


33°  BARNES    HOSPITAL. 

perature  at  different  beds>,  a  thing  which  it  is  often  desirable  to  accom- 
plish in  a  hospital. 

The  mean  velocity  of  the  upward  current  of  air  in  the  aspirating 
chimneys  is  about  180  feet  per  minute.  With  good  fires  in  the  grates 
at  the  base  of  the  flues  the  highest  recorded  velocity  was  700  feet  per 
minute. 

Each  chimney  under  ordinary  circumstances  removes  from  the  two 
wards  connected  with  it  about  36  cubic  feet  of  air  per  second,  or  1^2 
cubic  feet  per  second  per  man. 

This  supply  can  be  at  any  time  doubled  by  the  use  of  the  fan. 
When  fires  are  used  at  the  base  of  the  chimneys  to  accelerate  the  aspir- 
ation the  consumption  of  coal  is  about  30  pounds  of  anthracite  per 
hour  per  grate. 

The  following  data  are  taken  from  a  report  which  was  printed  for 
the  use  of  trustees  of  the  Johns  Hopkins  Hospital,  in  Baltimore,  but 
which  was  never  published,  and  is  now  rare.  The  observations  were 
made  and  reported  by  Surgeon  D.  L.  Huntington,  U.  S.  Army,  to 
whose  superintendence  much  of  th'e  success  of  the  system  was  due. 

The  following  are  instances  of  experimental  use  of  the  fan  : 

June  7.  External  air  75°  F.:  5  p.  M.,  temperature  of  air-supply  duct  68°  F., 
20  pounds  steam;  120  revolutions  of  fan  per  minute. 

Velocity  of  air  at  throat  of  duct  (40  square  feet  area)  1,350  feet  per  minute 
at  the  nearest  inlet  into  ward  : 

ist  story  (100  feet  from  throat) 450  feet  per  minute. 

2d     "         118     "  "         420     " 

3<i  132  340     ' 

At  most  remote  inlet  into  ward  : 

ist  story  (298  feet  from  throat) 410  feet  per  minute. 

2d     "         315     "  "         220     " 

3d  33i  "         139     "• 

On  this  trial  all  registers  were  open,  also  all  doors,  windows,  and 
ventilating  outlets,  the  resistance  to  the  fan  being  reduced  to  a 
minimum. 

Nov.  i.  Temperature  of  external  air  45°  F.,  of  duct  46°  F.,  20  pounds 
steam  ;  120  revolutions  of  fan  per  minute. 

Velocity  of  air  at  throat  of  duct  1,320  feet  per  minute  at  the  nearest  inlet 
to  ward: 

ist  story  (same  distance  as  above) 530  feet  per  minute. 

2d      "  "         360 

3d      "  "         269        *'  " 

At  most  remote  inlet  into  ward: 

ist  story 750  feet  per  minute. 

2d      " 500        "  " 

3d      "      298 


BARNES    HOSPITAL. 


331 


In  this  experiment  all  windows  and  doors  were  closed,  the  venti- 
lating registers  and  outlets  being  open. 

It  will  be  seen  that  in  the  first  experiment  the  pressure  of  the  air 
as  indicated  by  the  velocity  was  greatest  at  the  inlets  nearest  the  fan, 
while  the  reverse  was  the  case  in  the  last  trial.  The  direction  and  force 
of  the  prevailing  wind  also  has  a  very  considerable  influence  on  the 
movement  of  air  through  the  fan  and  in  the  duct.  Dr.  Huntington 
remarks  that  "  a  long  series  of  experiments  at  different  seasons  of  the 
year  have  all  yielded  harmonious  results.  Beyond  a  velocity  of  from 
800  to  900  feet  per  minute  in  the  main  duct,  the  effective  force  of  the 
air  is  much  impaired,  and  the  result  usually  seen  at  the  inlets  nearest 
the  fan  is  a  lessened  current.  The  general  rule  in  working  the  fan  is 
to  use  15  pounds  of  steam  and  not  over  60  revolutions  per  minute, 
equal  to  from  400  to  600  feet  per  minute  in  the  duct;  this  gives  all  the 
air  needed  for  the  building,  and  brings  the  consumption  of  fuel  to  its 
lowest  point.  With  this  velocity  air  enters  the  wards  at  the  rate  of 
from  2  to  4  feet  per  second." 

A  specially  interesting  experiment  was  made  in  one  of  the  wards 
on  the  night  of  November  28,  which  is  thus  reported  by  Dr.  W.  M.  Mew, 
who  made  the  air  analyses.  Ward  B  (for  12  beds)  contained  n 
patients;  the  ordinary  ventilation  was  going  on. 

Ward  D  had  12  beds;  all  occupied.  All  the  outlets  had  been 
closed  for  35  minutes  before  the  first  experiment,  in  order  to  make  the 
air  thoroughly  impure,  which  was  accomplished,  as  is  shown  by  the 
high  percentage  of  carbonic  acid  obtained. 

The  second  experiment  was  made  in  the  same  ward  just  10 
minutes  later,  during  which  time  the  outlet  and  inlet  flues  were  open 
and  the  fan  making  60  revolutions  per  minute. 

It  will  be  seen  from  the  following  table  that  the  use  of  the  fan  in 
this  way  for  10  minutes  made  the  very  impure  air  of  the  ward  nearly 
as  pure  as  the  outer  air  : 


AIR,  WHENCE  TAKEN. 

TEMPERATURE. 

Difference. 

Relative 
Humidity. 

Vols.ofCO2 

in  10,000. 

Dry  Bulb. 

Wet  Bulb. 

putside 

49°  F. 
68°  F. 
77°  F. 
80°  F. 

45°  F. 
57°  F. 
6i°F. 
66°  F. 

4 
II 
16 
14 

73 
40 
38 

3.05 
6.35 
11.23 

3-75 

Vard  B     

Ward  I  ist  experiment 

D       \  2d 

332 


NEW    YORK    HOSPITAL. 


At  the  time  of  this  observation  there  was  very  little  wind,  the 
barometer  was  29.72,  the  temperature  in  the  aspirating  chimneys  was 
79°  F.,  and  the  average  velocity  of  the  upward  current  in  them  was 
120  feet  per  minute. 


FIG.  96.— NEW  YORK  HOSPITAL  BUILDINGS.— PLAN  OF  CELLAR. 


A.— Stairs.  ^.—Boiler.  /.—Fan  blower. 

B. — Corridor.  F. — Engine  room.       J. — Cold-air  duct. 

C.— Elevator.  G.—  Fresh-air  duct.     A".— Steam  coils. 

D, — Boiler  room.       H, — Engine.  L. — Ash  vaults. 

Q. — Ice  house. 


M.—  Coal  vaults. 

TV. -Vaults. 

a— Area. 

P.—  Vegetable  vaults,  etc. 


The  placing  of  the  kitchen  in  the  third  story  of  the  hospital  has 
been  a  decided  success  in  more  ways  than  one.  The  odors  from  cook- 
ing are  almost  entirely  excluded  from  the  building,  although  sometimes 


NEW   YORK    HOSPITAL.  333 

the  lift  which  passes  from  the  kitchen  to  the  dining  room  acts  as  a  sort 
of  air-pump,  and  draws  or  forces  some  of  the  air  from  the  kitchen 
down  to  the  second  floor. 

This  principle  of  placing  the  kitchen  on  the  upper  floor  was 
adopted  in  the  New  York  Hospital,  the  plans  for  which,  prepared  by 
the  architect,  Mr.  George  B.  Post,  were  adopted  in  1875. 

This  hospital  is  located  near  the  center  of  New  York  City,  and  is 
an  illustration  of  an  attempt  to  make  up  in  height  for  deficiency  in 
ground  area. 

The  general  arrangement  is  shown  in  the  accompanying  plans, 
which  are  copied  from  those  prepared  by  the  architect  to  illustrate  his 
description  of  the  building,  which  is  of  brick,  and  contains  163  beds. 
In  the  wards  there  is  one  window  to  each  bed,  each  external  pier  of 
the  building  being  a  flue,  which  is  lined  with  hollow  bricks  to  prevent, 
as  far  as  possible,  loss  of  heat  by  radiation.  Through  the  center  of 
these  flues  run  cast-iron  pipes,  intended  to  be  fitted  so  as  to  be  air- 
tight, and  through  which  fresh  air  is  taken  to  the  building,  being 
forced  in  by  a  fan. 

The  spaces  outside  these  fresh-air  pipes  are  the  foul-air  flues. 
These  terminate  above  in  pipes  leading  to  an  exhaust  fan,  which  is 
located  in  the  top  of  the  center  building. 

The  heating  is  by  steam,  the  coils  being  arranged  at  the  bottom 
of  the  fresh-air  pipes  in  such  a  way  that  by  a  valve  the  cool  air  from 
the  propelling  fan  can  be  sent  either  through  or  around  the  heating 
coil.  The  fresh  air  is  admitted  to  the  wards  through  slits  in  the 
window  sills,  forming  a  jet  directed  upward  on  the  principle  of  Tobin's 
tubes.  A  similar  arrangement  exists  in  the  pavilion  of  the  London 
Hospital,  erected  in  1875-6. 

The  openings  for  the  exit  of  foul  air  from  the  wards  are  in  part 
placed  in  the  walls  of  the  piers  and  in  part  beneath  the  beds. 

No  effort  or  cost  was  spared  in  the  construction  of  this  building  to 
overcome  the  difficulties  connected  with  the  arrangement  of  heating 
and  ventilation  of  a  building  of  so  many  stories,  all  of  which  through 
the  staircase  halls  and  elevator  shafts  are  practically  in  free  communi- 
cation with  each  other,  and  a  fair  amount  of  success  has  been  attained. 
I  do  not  know  of  any  published  observations  showing  what  the  actual 
operation  of  the  apparatus  is,  but  I  have  visited  the  hospital  several 
times,  and  have  twice  tested  the  currents  with  an  anemometer.  These 
testings  made  the  average  air  supply  to  be  about  2,400  cubic  feet  per 
bed  per  hour — an  insufficient  amount,  if  all  the  beds  were  full,  which, 
however,  was  not  the  case. 


334 


NEW    YORK    HOSPITAL. 


The  principle  of  placing  fresh-air  pipes  inside  of  the  foul-air  ducts 
is  one  that  cannot  be  approved  of  for  hospital  ventilation,  for  although 
the  fresh-air  pipes  are  of  iron,  and  may  have  been  tightly  fitted,  it  is  a 


FIG.  97.— NEW  YORK  HOSPITAL  BUILDINGS.— PLAN  OF  SECOND,  THIRD  AND 

FOURTH  STORIES. 


MAIN  BUILDING. 
A.—  Stairs.              £.—  Nurses'  room. 
B.  —  Corridor.         H.  —  Dining  room. 
C.—  Elevator.           /.—Dumb  waiter. 
D.—  Hall.                 /.—Ventilating  duct. 
E.—  Closet.             Jr.—  Balcony. 
F.—  Ward. 

WEST  WING. 
a.—  Bath-room. 
£.-Sink. 
c.—  Toilet  room, 
d.  —  Corridor. 

EAST  WING. 
*.—  Bath-room. 
/.—Sink. 
<p-.—  Toilet  room. 
n.  —  Corridor. 

ADMINISTRATION  BUILDING. 
Library  and  Museum  Floor. 


mere  question  of  time  when  some  communication  will  be  established 
between  the  inner  and  outer  surfaces  of  these  pipes,  either  by  rusting 
or  by  alternate  expansions  and  contractions,  and  then  the  foul  air  may 


NEW    YORK    HOSPITAL. 


335 


be  carried  back  into  the  wards.  The  iron  pipes  are  not  readily 
accessible,  being  enclosed  in  the  walls,  and  there  is  no  ready  means  of 
determining  their  condition. 


FIG.  98.— NEW    YORK    HOSPITAL    BUILDINGS.  — DIAGRAM    OF    VENTILATION 

AND   HEATING. 


A.— Main  fresh-air  shaft  from  blower. 

.5.— Connection  to  steam  coil. 

C.— Steam  coil. 

D.— Cold-air  passage  around  steam  coil. 

E. — Valve  to  regulate  temperature  by  pass- 
ing any  required  portion  of  the  air 
around  the  steam  coils. 

.F.— Hot-air  pipes. 

G. — Connections  to  registers. 

H.- Register  box  and  opening. 


/.-Ventilating  fluef  containing  hot-air 
pipes. 

A'.— Main  orifices  for  ventilation. 

L. — Orifices  for  ventilation  for  occasional 
use. 

^/.—Ventilating  pipes. 

N.— Trunk  ventilating  pipes  leading  to 
exhaust  blower. 

O.— Plans  of  connections  of  hot-air  pipes. 

P> — Sections  through  connections  of  hot- 
air  pipes. 


336 


JOHNS    HOPKINS    HOSPITAL. 


One  of  the  most  satisfactory  of  existing  hospitals  as  regards  its 
heating  and  ventilation  is  the  Johns  Hopkins  Hospital,  in  Baltimore, 
the  block  plan  of  which  is  shown  in  Fig.  99. 


FIG.  Q9.-BLOCK  PLAN  OF  JOHNS  HOPKINS  HOSPITAL. 

A.— Administration  tuilding.  .S1.— Stable 

B  C.— Pay  wards.  T,—  Janitor's  lodge. 

D  E.— Two-story  octagon  ward.  U.—  Amphitheater. 

F  G  ^.—Common  wards.  X.— Apothecaries'  building. 

/.—Isolation  ward.  F.— Baths. 

K. Kitchen.  Fig,  2. — Cross-section  of  corridor  and  pipe 

/,. Laundry.  tunnel  beneath. 

N.— Nurses'  home.  Figs.    3-4.  — Cut-off    valve    on    hot-water 

C?.— Dispensary.  main. 
R.— Mortuary. 


JOHNS    HOPKINS    HOSPITAL. 


337 


In  this  hospital  the  heating  of  all  the  wards  and  of  the  adminis- 
tration and  apothecaries'  buildings,  the  nurses'  home  and  the  kitchen  is 
effected  by  hot  water,  the  heat  being  furnished  by  four  boilers  in  the 
vaults  of  the  kitchen  building  and  two  in  the  cellar  of  the  nurses' 


FIG.  loo.— FLOOR  PLAN  OF  COMMON  WARD,  JOHNS  HOPKINS  HOSPITAL. 


r  ?         * 

FIG.  loi.— BASEMENT  AND  ATTIC  PLANS  OF  COMMON  WARD. 

home,  each  boiler  being  16  feet  long,  5  feet  in  diameter  and  containing 
106  3^-inch  tubes.  The  outflow  main  is  26  inches  in  inside  diameter 
and  the  entire  system  contains  about  175,000  gallons  of  water. 


338 


JOHNS    HOPKINS    HOSPITAL. 


The  heating  of  the  amphitheater  and  dispensary  is  effected  by 
low-pressure  steam  from  boilers  at  the  kitchen  building.  Figure  100 
shows  the  main  floor  plan,  Fig.  lot  the  basement  and  attic  plans,  Fig. 
102  a  longitudinal  section,  and  Fig.  103  a  cross-section  of  one  of  the 
common  wards. 

The  common  wards  are  each  contained  in  a  separate  pavilion  of 
one  story  with  a  basement.  The  basement  is  devoted  entirely  to  heat- 
ing and  ventilation  purposes,  forming  practically  a  large,  clean  air 
chamber  containing  the  hot-water  coils  for  heating,  and  from  which  the 
air  supply  for  these  coils  can  be  taken  when  desired.  Usually,  how- 
ever, the  supply  is  taken  directly  from  the  external  air.  Each  of  these 


FIG.  I02.-LONGITUDINAL  SECTION  OF  COMMON  WARD. 

wards  is  practically  a  separate  small  hospital,  and  it  is  impossible  to 
pass  from  one  ward  to  another,  or  from  the  corridor  which  connects 
the  basements  to  the  wards,  without  going  into  the  open  air. 

Each  of  the  wards  has  a  separate  aspirating  chimney,  located  as 
shown  in  the  plans,  in  an  octagonal  hall  or  vestibule  on  the  connecting 
corridor.  Into  this  chimney  empties  a  foul-air  duct,  which  runs  longi- 
tudinally beneath  the  center  of  the  floor  of  the  ward,  and  which  re- 
ceives the  air  from  lateral  ducts  opening  beneath  the  foot  of  each  bed. 
The  main  foul-air  duct  is  made  of  wood,  lined  with  galvanized  iron, 
and  the  lateral  pipes  are  of  galvanized  iron,  and  cylindrical  in  shape. 

A  similar  duct  is  placed  above  the  ceiling  and  communicates  with 
the  ward  by  five  openings  in  the  ceiling,  in  the  longitudinal  central 


JOHNS    HOPKINS    HOSPITAL. 


339 


axis.  Just  above  where  this  upper  duct  enters  the  chimney,  there  is 
placed  in  the  shaft  a  coil  to  be  heated  by  high-pressure  steam  when  it 
is  necessary  to  quicken  the  aspirating  movement. 

It  will  be  seen,  therefore,  that  the  foul  air  can  be  taken  either  at 
the  level  of  the  floor  beneath  the  beds  or  from  the  center  of  the  ceil- 
ing ;  the  first  method  being  employed  in  winter  and  the  second  in 
summer. 


FIG.  103.— CROSS-SECTION  OP  COMMON  WARD. 
V. — Lower  foul-air  duct.    X. — Upper  foul-air  duct. 


The  main  central  aspirating  chimney  is  devoted  to  the  ventilation 
of  the  ward  only.  All  the  service  rooms  have  separate  and  independ- 
ent exit  shafts  of  galvanized  iron  passing  up  through  the  roof,  and 
capped  with  a  modification  of  the  Emerson  ventilator. 


340 


JOHNS    HOPKINS    HOSPITAL. 


One  of  the  common  wards  has  a  small  propelling  fan  placed  in  the 
basement,  the  ducts  from  which  open  beneath  the  heating  coils,  the 
object  being  to  secure  a  thorough  air  flush  of  the  ward  two  or  three 
times  a  day,  and  also  to  supplement  the  aspirating  shaft  on  the  very 


FIG.  104. 


C. — Central  ventilating  chimney. 

V  W.—  Water-closet  vent  shaft,  24  inches  in 

diameter. 

W  C1.— Closet  vent  shafts. 
P  W.—  Vent  flues  for  private  wards. 


DR. — Dining-room  vent  flue. 
CL  V.—  Soiled  clothes-lift  vent. 
F  V.— Food-lift  vent. 

PL   V. — Patients' clothing  and  clean  linen 
vent  shaft. 


few  days  of  the  year  when  such  aid  may  be  useful,  but  it  has  been 
found  that  the  aspirating  chimney  is  sufficient  to  do  ail  that  is 
required,  and  hence  such  fans  have  not  been  placed  in  the  other  wards. 
Figure  104  is  a  transverse  section  of  service  building  of  common 
ward  through  kitchen,  showing  foul-air  ducts. 


JOHNS    HOPKINS    HOSPITAL. 


341 


In  the  two-story  Octagon  Ward  the  foul-air  aspirating  chimney  is 
placed  in  the  center  of  the  ward  as  shown  in  the  section  of  this  build- 
ing given  in  Fig.  105. 

This  chimney  is  8  feet  in  diameter  internally,  and  has  on  each 
face  two  openings  from  the  ward — one  near  the  floor,  the  other  near 
the  ceiling— each  being  20x26  inches. 

Within  this  chimney  is  set  a  tube  of  boiler  iron,  5  feet  9  inches  in 
diameter,  resting  on  a  projecting  cast-iron  base,  and  extending  from 
the  ceiling  of  the  lower  ward  to  above  the  ceiling  of  the  upper  one. 


FIG.  105— LONGITUDINAL  SECTION  OF  THE  OCTAGON  WARD. 


Into  the  space  between  this  iron  tube  and  the  brick  wall  of  the  chim- 
ney the  openings  from  the  upper  ward  enter,  and  just  above  the  top 
of  the  iron  flue  is  the  accelerating  steam  coil.  In  these  wards  the 
general  direction  of  the  air  currents  is  from  the  circumference  toward 
the  central  shaft. 

Figure  106  is  a  transverse  section  through  the  water  closets  of 
this  ward,  showing  foul-air  flues. 

Figure  107  shows  main  floor  plan  and  transverse  section  of  one  of 
the  pay  wards,  Fig.  108  a  longitudinal  section,  and  Fig.  109  a  trans- 


342 


JOHNS    HOPKINS    HOSPITAL. 


verse  section,  showing  together  the  arrangement  of  fresh-air  and  foul- 
air  ducts. 

The  results  of  the  above-described  heating  and  ventilating  appa- 
ratus have  been  very  satisfactory.  In  the  wards  the  proportion  of 
carbonic  impurity  due  to  respiration  has  been  found  to  be  about  2 
parts  in  10,000. 


FIG.  106. 


The  largest  and  most  costly  hospital  recently  constructed  is 
probably  the  new  City  Hospital  near  Hamburg,  opened  in  1890,  and 
containing  about  1,300  beds.  The  basement  and  main  floor  plans  of 
one  of  the  one-story  ccmmon  wards  are  shown  in  Figs,  no  and  in, 
the  longitudinal  section  in  Fig.  112,  and  transverse  sections  in  Figs- 
113  and  114. 


HAMBURG    HOSPITAL. 


343 


In  these  wards  the  heating  is  effected  by  heating  the  entire  floor 
on  the  principle  of  the  ancient  Roman  hypocaustum.  Beneath  the 
floor,  as  shown  in  the  sections,  are  flues  about  30  inches  square,  inter- 
nal measurement,  constructed  of  brick  and  concrete,  and  covered  by 


5ETCT.ON 


FIG.  107. 

cement  and  marble  tiles  forming  the  ward  floor.  In  these  flues  are 
placed  the  steam-heating  pipes.  The  air  admitted  through  the  fresh- 
air  inlets  can  be  warmed  by  the  radiators,  H,  shown  in  the  figures. 
The  foul  air  escapes  by  openings  at  the  ridge. 


344 


JOHNS    HOPKINS    HOSPITAL. 


FIG.  109. 


HAMBURG    HOSPITAL. 


345 


H 


1 


FIG.  iTo.-BASEMENT  PLAN. 

A.—  Transverse  corridor.  //.—Radiators. 

/?.— Boiler  room.  r.— Soiled-clothes  chute. 

C.—  Coal  vaults.  r;.— Air  ducts. 

D.— Store-rooms  for  utensils.  w.— Separating  walls  in  hot-air  flues 

/T.— Stoker's  room. 


under  floor. 


WARD 

DP  EH  cn  B  on 

JH 


A. — Transverse  corridor. 

/?.— Isolating  rooms. 

//.—Radiators. 

N. — Attendant's  room. 

R. — Landings. 

/.— Washstand. 

m. — Rinsing  basins. 

«.— Tables. 


FIG.  m. 

o. — Glass  table  for  utensils. 

/.—Clothes  presses. 

r. — Soiled-clothes  chute. 

s.— Cabinet  for  bandages. 

/._ Washstand  and  writing  table. 

«.— Bandaging  table. 

v. — Air  ducts. 


A.—  Transverse  corridor. 
C— Coal  vaults. 
//.—Radiators. 


FIG.  112. 

/.—Air  chambers  (Luftkanale). 
K.— Space  or  chamber  for  pipes  for 
heating  floor. 


346 


INSANE    ASYLUMS. 


The  general  principles  to  be  observed  in  the  ventilation  of  insane 
asylums  are  much  the  same  as  those  for  other  hospitals,  but  are  modi- 
fied by  the  necessity  of  providing  for  a  much  larger  number  of  single 
rooms  opening  from  a  common  corridor.  As  a  rule,  steam  heating 
and  propelling  fans  are  used  in  American  asylums,  and  in  some  of 
the  larger  ones  the  plant  is  an  extensive  one. 

Figure  115  shows  half  basement  and  half  first-story  plan  with  sec- 
tion of  the  insane  asylum  for  New  Castle  County,  near  Wilmington, 
Del. 


FIG.  n3. 


FIG.  114. 

It  is  three  stories  in  height,  with  a  basement — the  latter  unoccu- 
pied except  with  a  kitchen  and  dining  rooms  for  the  employees.  The 
rooms  for  the  patients  are  on  an  average  12x14  feet,  with  a  height  on 
the  first  floor  of  12  feet  and  on  the  other  floors  of  10  feet  6  inches, 
with  four  large  rooms  on  each  floor  at  the  extremes  of  each  wing;  the 
executive  offices  being  in  the  center  on  the  first  and  second  floors 
while  above  is  a  large  room  occupying  the  whole  floor  of  the  center 
front. 

All  the  radiators  are  placed  in  the  basement  halls,  except  some 
few  direct  radiators,  marked  J?  on  the  plans,  which  are  either  used  in 
the  halls,  or  dining  rooms,  or  other  large  rooms  with  considerable  glass 
surface,  as  auxiliary  heaters. 


INSANE    ASYLUMS. 


347 


Every  room  has  a  warm-air  flue  of  9x13  inches  in  its  cross-section 
and  plastered.  These  flues  start  just  beneath  the  ceiling  of  the  base- 
ment in  the  halls  and  terminate  about  3  feet  above  the  base-board  in 
each  room.  At  the  opposite  side  of  the  room  in  the'  outside  walls  are 


FIG. 


vent  flues  of  the  same  dimensions,  with  the  registers  near  the  floor, 
but  instead  of  running  to  the  top  of  the  house  they  run  downward  in 
the  cold  walls  and  terminate  in  horizontal  foul-air  ducts  underneath 
the  basement  floor.  These  ducts  which  are  marked  S  on  the  elevation 


348 


INSANE    ASYLUMS. 


section,  connect  with  vertical  shafts  s  s  s  on  ground  plans,  and  with 
the  annular  space  around  the  cast-iron  boiler  chimney  in  a  similar 
shaft.  The  vertical  shafts  are  each  warmed  by  steam  coils  of  150 
square  feet  of  radiator  surface  arranged  in  coils  which  run  around  the 
inside  of  the  shafts  3  inches  from  the  walls,  and  covering  them  for  a 
height  of  about  60  inches;  their  position  being  on  a  level  with  the 
first-story  floor,  and  about  one-quarter  of  the  height  of  the  stack 
from  the  bottom. 


srrzx/. 

m 

THROUGH-  ff\ONT  HALL  "    %£ 


FIG.  n6. 


Through  the  front  halls  the  hoods,  Fig.  116,  are  opened  at  the 
bottom,  the  whole  hall  being  an  air  duct.  Air  is  taken  in  under  the 
room  A,  first  story,  or  through  the  room  B,  in  the  basement,  as  may 
be  desired,  dependent  upon  the  direction  of  the  wind.  Here  it  is 
warmed  slightly  before  it  passes  to  the  hall,  and  in  the  hall  it  again 
receives  heat  from  the  main  and  return  pipes  and  connections.  This 


INSANE    ASYLUMS. 


349 


hallway  is  a  reservoir  of  tempered  air,  which  is  drawn  into  the  hoods 
by  the  displacement  and  rarification  within  the  radiator.  The  inner 
walls,  being  honeycombed  with  flues,  become  heated  in  a  short  time  to 
a  temperature  considerably  above  the  air  of  the  building,  after  which 
the  air  from  the  radiators  loses  no  heat  in  its  passage  through  these 
flues,  and  hence  has  a  comparatively  high  velocity  and  power. 

Figure  117  is  a  section  through  a  rear  hall,  used  as  a  passageway. 
In  this  case  the  hoods  return  at  the  bottom  to  a  second  opening  in 


THffOUGH  nCAR  H/ILL 
FIG.  n7. 


the  wall,  through  which  they  receive  their  air  from  a  duct  underneath 
the  hall  floor. 

Figure  118  is  a  plan  of  the  indirect  heaters  and  the  heat  flues. 

For  further  particulars  consult  The  Sanitary  Engineer  of  Decem- 
ber 25,  1884. 


BARRACKS. 


In  connection  with  the  subject  of  hospital  ventilation  may  be  con- 
veniently considered  that  of  barracks  for  soldiers,  since  much  the  same 
principles  apply  to  each,  the  chief  differences  being  that  there  are 
greater  opportunities  for  aeration  in  barracks,  and  the>  require  a  less 
supply  of  air  per  head. 

In  past  times  in  all  armies  the  overcrowding  of  and  want  of  venti- 
lation in  barracks  has  caused  much  disease  and  loss  of  service,  and,  as 
a  rule,  the  more  permanent  and  costly  the  buildings  the  more  defective 
they  have  been  in  air  supply.  The  cheap  wooden  barracks  of  many  of 


FIG.  us. 


our  military  posts,  built  of  unseasoned  lumber  and  full  of  cracks  and 
crevices,  are  in  many  respects  healthier  than  casemate  quarters,  or  than 
the  solidly  constructed  buildings  of  brick  or  stone  which  are  provided 
for  soldiers  in  many  other  countries. 

The  amount  of  cubic  space  per  head  to  be  furnished  in  barracks 
is  fixed  by  regulation  in  most  foreign  countries.  For  the  English 
Army  it  is  600  cubic  feet;  for  the  German  and  Austrian  armies,  527 
cubic  feet,  with  48  square  feet  of  floor  share  per  man;  for  the  French 
Army,  424  cubic  feet  for  infantry,  and  495  cubic  feet  for  cavalry;  for 


BARRACKS.  351 

the  Belgian  Army,  555  cubic  feet.  The  Indian  Army  regulations  call 
for  90  square  feet  of  floor  surface,  and  1,800  cubic  feet  of  space  per 
man  in  barracks  on  the  plains,  the  barracks  to  be  two-storied,  with  a 
veranda  10  feet  wide,  the  rooms  to  be  24  feet  wide  and  20  feet  high, 
and  not  more  than  24  men  are  to  be  placed  in  one  room. 

For  the  United  States  Army  there  are  no  definite  regulations  as  to 
floor  space  or  cubic  space  in  barracks,  but  in  the  permanent  barracks 
of  recent  construction  at  our  larger  posts  from  600  to  800  cubic  feet  of 
air  space  per  man  are  provided,  and  the  rooms  are  usually  12  feet  high, 
giving  from  50  to  65  square  feet  of  floor  space  per  head. 

These  permanent  barracks  are  heated  by  steam,  the  precise 
method  varying  at  different  posts.  In  the  Cavalry  Barracks  at  Fort 
Sheridan  the  heating  is  by  indirect  radiation,  there  being  four  inlets, 
each  1 6  inches  square,  for  a  room  measuring  68'x4i'xi2',  and  contain- 
ing 45  men. 

The  exit  flues  in  the  walls  are  nine  in  number,  two  12x20  inches, 
two  8x12  inches  and  five  i  foot  square  each,  and  all  these  flues  collect  in 
the  attic  to  a  central  shaft  in  which  is  placed  an  accelerating  steam 
coil.  With  a  velocity  of  between  5  and  6  feet  per  second  at  the  inlets, 
and  of  4  feet  per  second  in  the  outlet  flues  a  good  air  supply  will  be 
secured. 

Figures  119  and  120  show  first  and  second  floor  plans  of  half  of  a 
two-story  barracks  for  infantry  as  proposed  for  an  U.  S.  Army  Post  in 
process  of  construction  by  Capt.  George  E.  Pond,  A.  Q.  M.,  who  has 
kindly  furnished  them  with  the  following  notes  :  These  plans  provide 
for  28  men  in  a  dormitory,  giving  to  each  man  70  square  feet  of  floor 
space  and  840  feet  of  cubic  space.  The  heating  may  be  by  direct-indirect 
radiators  placed  beneath  the  windows  or  by  indirect  radiation  by  a  hot 
blast  system,  the  fresh-air  flues  being  in  the  outer  walls.  The  foul-air 
upcast  shafts  c  c  are  384  square  inches  in  cross-section,  with  open- 
ings both  at  ceiling  and  floor,  the  latter  always  open,  the  upper  one 
controlled  by  a  shutter  hinged  at  the  top.  These  shafts  unite  in  the 
attic  into  a  single  shaft,  which  rises  above  the  roof  and  is  capped  with 
a  cowl.  If  direct-indirect  heating  is  used  an  accelerating  steam  pipe 
is  placed  in  each  upcast  shaft.  Six  Sheringham  valves  are  placed  in 
the  outer  walls  near  the  ceiling.  A  A  and  B  B  are  foul-air  upcast 
shafts.  D  indicates  interior  wall  flues  which  might  be  used  for  stoves 
in  case  of  emergency,  but  which  ordinarily  are  upcast  flues  having 
registers  in  place  of  stove-pipe  openings. 

Figure  121  is  a  floor  plan  of  half  of  a  double  barrack,  which  may 
be  called  the  present  standard  plan  of  the  Quartermaster  Department 


352 


BARRACKS. 


FIG.  119. 


BARRACKS. 


353 


JW/7 


yjjNJO 


FIG.  120. 


354 


BARRACKS. 


for  permanent  posts,  and  for  which  I  am  indebted  to  the  courtesy  of 
Captain  Miller,  A.  Q.  M.  The  upcast  shafts  A  B  are  in  the  corners 
of  the  dormitory,  four  on  each  floor.  R  are  radiators,  part  of  which 
are  direct,  and  part  direct-indirect. 


DORM/ TORY 


DAY  ROOM. 

24-6XJ3X/2' 


FIG. 


The  most  recent  work  on  the  construction  and  ventilation  of  bar- 
racks is  "Putzeys"  (F)  and  Putzeys  (E.)  Hygiene  des  agglomerations 
militaires,  la  construction  des  casernes,"  8  vo.,  Liege,  1892 — with  an 
atlas  of  10  plates  relating  mainly  to  Belgian  barracks. 


CHAPTER  XV. 

VENTILATION  OF  HALLS  OF  AUDIENCE  AND  ASSEMBLY  ROOMS.  THE 
HOUSE  OF  PARLIAMENT.  U.  S.  CAPITOL.  THE  NEW  SORBONNE. 
THE  NEW  YORK  MUSIC  HALL.  THE  LENOX  LYCEUM. 

SOME  of  the  most  difficult  problems  in  ventilation  are  met  with  in 
large  assembly  rooms,  or  halls  of  audience,  including  legislative 
halls,  churches,  theaters,  music  halls,  etc.  These  may  be  divided  into 
three  classes,  each  presenting  certain  peculiarities  which  have  an  im- 
portant bearing  upon  the  arrangements  for  their  heating  and  venti- 
lation. 

The  first  class  includes  the  assembly  halls  used  by  legislative 
bodies;  the  second,  the  majority  of  churches  and  theaters,  and  the 
third,  lecture  rooms  and  other  assembly  rooms  located  in  the  second  or 
third  stories  of  large  buildings,  in  which  the  rooms  below  are  occupied 
for  other  purposes,  and  are  not  available  for  heating  and  ventilating 
apparatus. 

Legislative  assembly  halls  differ  from  most  other  halls  of  audience 
in  that  they  may  at  times  be  occupied  for  many  hours  continuously. 
The  number  of  persons  in  them  is  liable  to  vary  greatly  and  suddenly 
and  it  is  desirable  that  a  person  speaking  on  any  part  of  the  floor 
shall  be  distinctly  heard  by  persons  on  any  other  part  of  the  floor. 
Expense  of  construction  and  maintenance  is  usually  a  very  secondary 
matter. 

No  such  hall  has  been  yet  constructed  which  has  given  at  all  times 
satisfactory  results  to  all  of  the  legislators  who  have  used  it,  and  what- 
ever system  has  been  tried,  the  rule  is  that  in  a  few  years  at  latest 
the  complaints  become  so  numerous  and  emphatic  that  a  special  inves- 
tigation is  ordered  and  changes  of  some  kind  are  recommended.  The 
complaints  are,  for  the  most  part,  made  with  regard  to  unpleasant 
odors,  to  excessive  heat,  to  disagreeable  draughts  of  cold  air,  and  to 
interference  with  the  acoustic  properties  of  the  hall. 

Probably  no  legislative  hall  of  assembly  has  been  the  subject  of 
more  complaints,  or  of  more  experimental  changes,  than  have  those  of 


356  HOUSES    OF    PARLIAMENT. 

the  Houses  of  Parliament  in  London.  The  present  system  of  ventila- 
tion in  the  Houses  of  Parliament  is  a  modification  by  Dr.  Reid,  Sir  G. 
Gurney,  and  Dr.  Percy,  of  the  system  adopted  by  the  committee  of 
1840,  appointed  to  inquire  into  the  causes  of  the  frequent  complaints 
from  members  of  bad  ventilation  and  defective  communication  of 
sound. 

Ventilation  by  exhaustion  by  heated  shafts  has  been  used  in 
the  Houses  of  Parliament  until  recently,  when  a  plenum  system  has 
been  adopted. 

General  diffusion  of  the  fresh  air  being  the  desideratum,  the  floors 
of  the  houses  are  formed  of  cast-iron  gratings,  which  are  overlaid  (in 
the  House  of  Lords)  with  hair  carpet  and  with  coarse  hemp  netting 
(in  the  House  of  Commons).  These  gratings,  forming  the  ceilings  of 
the  equalizing  chambers,  allow  of  the  free  admission  of  a  large 
quantity  of  air  with  a  perfect  absence  of  draught. 

Below  the  equalizing  chambers,  and  communicating  with  them  by 
grated  openings,  is  another  chamber,  containing  the  heating  arrange- 
ment or  other  apparatus  for  such  treatment  of  the  air  as  the  state  of 
the  atmosphere  may  necessitate.  The  whole  of  the  space  occupied  by 
the  heaters  is  surrounded  by  a  gauze  screen,  which  acts  as  a  filter  to 
arrest  any  coarse  particles  of  dust,  etc.,  that  would  otherwise  pass  into 
the  house.  In  summer  the  air  is  more  or  less  freed  from  dust,  by 
passing  through  fine  water  spray. 

The  quantity  of  the  air  passing  is  regulated  by  a  sliding  door  or 
valve,  placed  in  the  foul-air  exit,  above  the  ceiling  of  the  house.  This 
is  actuated  by  hydraulic  arrangement,  and  is  under  the  control  of  the 
attendant  stationed  in  the  air  chamber  under  the  house. 

The  panels  of  the  ceilings  are  raised,  leaving  spaces  around  their 
edges,  through  which  the  foul  air  from  the  houses  is  drawn  off  up  to 
the  upcast  shafts. 

In  the  Commons  each  set  of  gas-burners  is  connected  by  a  vertical 
tube  with  a  main  flue  (running  the  length  of  the  ceiling),  in  connection 
with  the  upcast  shaft,  into  which  the  products  of  combustion  pass. 

It  was  formerly  considered  that  by  drawing  the  air  from  the  top 
of  one  of  the  towers  a  purer  supply  would  be  obtained  than  if  taken 
from  the  ground  level.  This  has  (in  London),  however,  proved  to  be 
a  fallacy;  the  air  thus  obtained  was  the  most  contaminated  with  smoke 
and  other  impurities. 

In  the  House  of  Commons  the  air  inlets  were  formerly  placed  in 
the  "star"  and  ''commons"  courts,  but  now  consist  of  35  openings 
on  the  terrace,  each  having  an  area  of  a  little  over  9  square  feet. 


HOUSES    OF    PARLIAMENT. 


357 


During  the  hottest  weather  the  air  has  been  cooled  by  passing  it  over 
blocks  of  ice  placed  on  wooden  racks  in  the  airways. 

The  surface  of  the  ice  exposed,  however,  being  small  in  propor- 
tion to  the  volume  of  air  passing,  the  temperature  was  but  slightly 
reduced,  usually  not  more  than  one  degree  (i°),  yet  the  air  thus  treated, 
it  was  thought,  produced  a  sensation  of  freshness,  which  possibly  might 
be  due  to  the  condensation  by  the  ice  of  the  excess  of  moisture  present. 
This  was  particularly  noticed  on  one  occasion,  when  the  temperature 
of  the  air  was  nearly  the  same  before  and  after  passing  the  ice. 


FIG.  122. -SECTIONAL  ELEVATION  OF  THE  HOUSE  OF  LORDS  SHOWING 
WARMING  AND  VENTILATING  ARRANGEMENTS. 

The  fresh  air,  drawn  through  a  passage  in  which  are  spray  jets  for 
moistening  and  cooling  it  when  desirable,  is  forced  by  an  air  propeller 
through  a  canvas  screen  having  an  area  of  about  600  square  feet,  after 
which,  in  case  of  fog,  it  passes  through  a  loose  layer  of  cotton  batting, 
and  thence  to  the  warming  chamber  on  the  floor  of  which  the  heating 
batteries  B  B,  are  arranged  in  four  equidistant  and  parallel  rows. 


358 


HOUSES    OF    PARLIAMENT. 


FIG.  123.— HORIZONTAL  SECTION  THROUGH  EQUALIZING  CHAMBER  OF 
HOUSE  OF  LORDS. 


HOUSES    OF    PARLIAMENT.. 


359 


The  heated  (or  cooled)  air  ascends  through  gratings  C  C,  in  the  open- 
ings to  the  equalizing  chamber  Z>,  from  whence  it  is  distributed  to  the 


go^vs 

FIG.  124.— HORIZONTAL  SECTION  THROUGH  HOUSE  OF  COMMONS. 


360  .  JCAPITOL    AT    WASHINGTON. 

house  (through  the  grated  floor)  and  to  the  galleries  (by  the  openings 
and  flues  E  E). 

The  vitiated  air  is  drawn  off  through  the  openwork  in  the  ceiling 
to  the  foul-air  space,  in  communication  with  the  up-cast  shafts,  and 
also  through  openings  behind  the  bar  .F,  to  the  Victoria  tower  by  the 
down-pull  H,  as  shown  on  the  drawing. 

Figure  123  shows  a  horizontal  section  through  the  equalizing  cham- 
ber of  the  House  of  Lords.  The  lettering  is  the  same  as  on  Fig.  122. 

The  batteries  K,  are  for  heating  that  part  of  the  house  immedi- 
ately beneath  the  throne  ;  J/are  steam  pipes  for  heating  the  air  supply 
to  the  division  lobbies. 

-  In  a  report  of  a  Select  Committee  on  the  Ventilation  of  the  House 
of  Commons  made  in  1891,  it  is  recommended  that  the  size  of  the  in- 
take of  fresh  air  be  increased,  a  powerful  air  propeller  be  provided  and 
additional  facilities  for  the  entrance  of  fresh  air  be  obtained  both  for 
the  hall  and  for  committee  rooms. 

The  use  of  large  aspirating  chimneys  instead  of  fans  as  a  means 
of  ensuring  the  movement  of  air,  are  not  in  accordance  with  the  views 
of  modern  engineers,  or  with  their  ordinary  practice. 

Let  us  now  compare  with  the  above  the  arrangements  for  ventila- 
ting and  warming  the  halls  of  the  Senate  and  of  the  House  of  Repre- 
sentatives in  the  Capitol  at  Washington.  These  have  been  the  subject 
of  nearly  as  many  complaints,  investigations  and  reports  as  have  the 
Houses  of  Parliament,  but  the  actual  changes  made  have  not  been  so 
numerous. 

The  first  of  the  Congressional  documents  relating  to  this  subject, 
which  have  now  any  interest  or  value,  is  what  is  commonly  called  the 
Wetherell  Report,  being  Executive  Document  100  of  the  House  of 
Representatives  of  the  first  session  of  the  39th  Congress,  dated  May, 
1866. 

This  document  contains  briet  reports  by  Mr.  Walter,  the  architect, 
and  by  Professor  Joseph  Henry,  of  the  Smithsonian  Institution,  trans- 
mitting a  long  report  by  Dr.  Charles  Wetherell,  giving  the  results  of 
experiments  and  tests  made  by  him  to  determine  the  proportions  of 
carbonic  acid  present  in  the  hall  under  various  circumstances. 

These  results  showed  that  the  amount  of  carbonic  acid  present 
was  relatively  very  small,  and  that  the  gas  was  very  uniformly  diffused 
throughout  the  hall. 

The  report  gives  an  extensive  and  valuable  series  of  tables  com- 
paring these  results  with  those  obtained  by  other  investigators  in  lec- 
ture rooms. 


CAPITOL    AT    WASHINGTON.  361 

THE  FOLLOWING  TABLE  GIVES  SOME  OF    THE  RESULTS  REPORTED  BY  DR.  WETHERELL. 


d 

••7 

> 
c 

< 

"c 
6 
fc 

2. 

3- 

4- 

i 

7- 
8. 
9- 
io. 
i:. 

12. 

I3- 
'4- 

M- 

us. 

s 

19. 

2... 
21. 
2?. 

«3- 

24. 
15. 

26. 

a 

20. 

3'" 
|I- 

32- 
33- 

JJ- 

H 

£ 

*9- 

4»- 
4'- 
42- 

43- 

44- 

g 
9 

4'- 
JO. 

SI- 

52- 

53- 

34- 

55- 
36- 

57- 

53. 

59- 

Place  of  Observation. 

Date. 

Temperature  of 
Air,  Fahr.°. 

Relative 
Humidity. 

CARB.  ACID 

PER  10,000 
PER  VOL. 

Experi- 
ments 

1 

X 

Smithsonian  laboratory          

i864: 

June  27. 

44 

June  28. 

44 

44 

June  29. 

41 

June  30. 
July  2. 

1865. 
Jan  (  24. 

41 

Feb.   8. 

44 

Feb.  9. 

Feb.  15 
Feb.  16. 

41 

90.5 
86.9 
86. 
82.4 
84.2 
74-3 
77- 
77- 
77-0 
77-9 
78.8 

77-9 
78.8 
78.8 
78.8 
77.0 
78.8 
78.8 
78.8 
78.8 
78.8 
78.8 
88.2 
78.8 
84.2 
82.4 
84.2 
84.2 
82.4 
84.2 
84.6 
82.4 
84.2 
80.6 

61.9 
70.2 
70.9 
70.5 
72.0 

72-3 
29.8 
31-3 
33-8 
33-8 
33-8 
30.6 
30.6 
30-6 
70.  g 
70.9 
68. 
68. 
64. 

64. 
69.8 
35-2 

35-2 
72.7 

72.7 

47 
51 
50 
77 
58 
35 
34 
34 
32 
32 
30 

1 

36 
30 

1 

48 
62 
62 
62 
62 

S1 
80 

71 
74 
7i 
71 
7i 
7i 
7« 
74 
68 
74 

46 
32 
3* 
33 
27 
27 

5 

1 

65 
55 
55 
55 
20 

20 
21 
21 
27 

27 

44 

100 
IPO 

*6y2 

4&y2 

Capitol   N    E  portico 

Senate,  S   K.  corner,  over  ventilator  

Senate  opposite  chair 

'••'•• 

Senate,  ladies'  gallery,  S.  E.  corner  
Senate,  Sergeant-at-Arms'  office 

'.'.'.  '.'. 

Senate,  S.  E.  corner,  over  ventilator  
Senate,  opposite  chair 

Senate,  ladies'  gallery,  S.  E.  corner  

Smithsonian  laboratory                 ... 

Senate,  S.  E.  corner  ventilator..               

Senate  opposite  chair 

Senate,  ladies'  gallery,  S.  E.  corner.  ... 

Capitol   N  E  portico 

Smithsonian  laboratory  

3-345 
3-172 
6.793 
4-185 
4.902 
4-147 

3-258 
5,489 

Capitol,  main  portico 

Capitol,  main  portico,  2d  experiment 

House  of  Representatives,  N.  W.  corner  
House  of  Representatives,  2d  experiment  
House  gallery,  behind,  clock.  ... 

House  gallery,  2d  experiment  
Smithsonian  laboratory 

4.525 

Capitol,  N.  E.  portico.. 

.. 

Senate,  t  over  S.  E.  corner  ventilator  ,  

Senate,  six  feet  from  ventilator 

Senate,  opposite  chair  

Senate,  over  opposite  ventilator 

Senate,  six  feet  from  ventilator  

Senate,  N  .  W.  corner  ... 

Senate  over  side  ventilator 

Senate,  ladies'  gallery,  S.  E.  corner  
Senate,  stairs  to  gallery,  opposite  ventilator  

Senate,  post-office,  near  a  closed  window 

Senate,  post-office,  on  mantelpiece 

Senate,  ladies'  gallery,  near  reporters'  gallery  
Senate,  ladies'  gallerv,  near  diplomatic  gallery 

Senate  air  entering  fan  . 

Senate,  external  air,  north  portico     ...     

Smithsonian  Institution,  external  air  

44                                            44                                    44                     44 

2.722 
2.685 
2.719 
2.700 
2.659 
2.587 
5-491 
5-y79 

3.871 

4-085 
4.733 

4.443 
4.340 
2-637 

2.785 

3-405 

3.608 

2.709 
2.649 

5-735 
3.978 

4-588 

2.711 

3-552 

44                                           44                                    44                     44 

Senate  air  entering  fan 

Senate,  air  entering  fan,  2d  experiment.  . 

Senate,  air  entering  fan,  3d  experiment 

Senate,  level  desks,  S.  E.  corner  
Senate,  level  desks,  2d  experiment 

Senate,  diplomatic  gallery  

Senate,  diplomatic  gallery,  2d  experiment 

•senate,  illuminating  loft,  N.  W.  corner,  over  ventilator 
Senate,  illuminating  loft,  N.   W.  corner,  over  venti- 
lator, 2d  experiment  

Smithsonian  Institution,  dining  room  of  the  secretary. 
House  of  Representatives,  air  entering  fan  
House  of  Representatives,  air  entering  fan,  2dexperi 
ment  

House  of  Representatives,  level  of  desks,  N.  W.  corner. 
House  of  Representatives,  level  of  desks,  N.  W.  cor- 
ner, 2d  experiment  

362 


CAPITOL    AT    WASHINGTON. 

DR.  WETHERELL'S  TABLE. — (Continued.} 


No  of  Analysis.  1 

Place  of  Observation  . 

Date. 

Temperature  of 

Air,  Fahr.  °. 

Relative 
Humidity. 

GARB.  ACID 

PER  10,000 
PER  VOL. 

Experi- 
ments. 

d 
• 

1 

60. 
61. 

62. 

6* 

64. 

65- 
66. 

67. 
68. 
69. 
70. 

71. 
72. 

73- 

74- 
75- 

76 
77- 

78. 

79- 
So. 
Sr. 
82. 
8.5- 
84. 
S3- 
86. 

87. 
88. 
89. 

90. 

91. 

92 

House  of  Representatives,  diplomatic  gallery 

Feb.  16 

Feb.  17. 
Feb.  18. 
Feb.  24. 

u 

Feb.  25. 
it 

H 

Feb.427. 

Mar 

Man  31. 

70.9 
70.9 
68.4 

68.4 
65.2 
68.4 
37-4 
37-4 
37-4 
66.9 
66.9 
70.9 
72-3 

72-3 
36.7 

69.4 
69.4 
69.8 

69.8 
5i-4 
71.6 
71.6 
71.6 
71.6 
64.2 
64.2 

65. 
68. 
68. 
68. 

74- 
8* 

46^ 
46^ 
48 

48 

57 
46 
67 
67 
67 
3i 

15 

28^ 
2sy2 

93 

43 
43 
4i 

4i 
49 
37 
35 
35 
35 
34 
34 

g 

60 
60 

63 
60 
44 

3-913 
3-157 
4.065 

3-751 
2.650 

5-189 

2.360 
2.825 
2.758 
4  275 
4  839 
4.814 
7.269 

7-355 

3-535 
3.908 

'1.648 
4,557 

7-312 

House  of  Representatives,  diplomatic  gallery,  2d  ex- 
periment   
House  of  Representatives,  illuminating  loft,  N.  E. 
corner  

Houseof  Representatives,  illuminating  loft,  2d  exper- 
iment                

Dwelling,  311  F  Street,  bed  room,  2d  story,  front  

Senate,  air  entering  fan  

Senate,  air  entering  fan,  2d  experiment     
Senate,  air  entering  fan,  3d  experiment  
Senate,  level  of  desks,  S.  E.  corner  
Senate,  level  of  desks,  2d  experiment 

Senate,  reporters'  gallery  

Senate,  illuminating  loft,  near  ventilator.  .  .     
Senate,  illuminating   loft,  near  ventilator  2d  experi- 
ment    .... 

House  of  Representatives,  air  entering  fan 

House  of  Representatives,  S.  W.  corner,  outer  circle 
of  desks  

House  of  Representatives,  center  circle  of  desks  
House  of  Representatives,  Hon.  Mr.  Daily's  desk 
House  of  Representatives,  S.  E.  corner,  outer  circle 
of  desks           .                   .... 

2.801 
2.901 

2.686 
9-342 
!o  574 
9.454 

17.184 
12.803 
12.680 

2.851 

House  of  Representatives,  air  entering  fan. 

House  of  Representatives,  S.  W.  corner  (as  above).  .  . 
House  of  Representatives,  center  (as  above) 

House  of  Representatives,  Hon.  Mr.  Baily's  desk  .. 
House  of  Representatives,  S.  E.  corner  (as  above)  
Dome,  top  of  balustrade  of  tholus  

Dome,  top  ot  balustrade,  2d  experiment  
Capitol,  first  platform  steps,  main  east  portico,  4  feet 
4%  inches  above  ground  .. 
Secondary  public  school.  Miss  Mills 

Primary  public  school,  Miss  Robinson  
Primary  public  school,  Miss  Hubbard..  
Public  school,  main  intermediate,  ist  division,  Mrs. 
Rodier,  air  entering  from  teacher's  desk  
Public  school  air  from  north  side  of  room  
Public  school,  air  from  south  side  of  room  :    

The  chief  poir^  of  controversy  in  the  various  schemes  which  have 
been  proposed  for  the  ventilation  of  these  and  other  assembly  halls  is 
as  to  whether  the  general  direction  of  the  ventilating  currents  should 
be  upward  or  downward.  We  have  commented  briefly  on  this  point 
in  speaking  of  outlets  and  inlets,  but  it  requires  special  consideration 
in  this  connection.  The  arguments  which  have  been  urged  in  favor  of 
the  down-draught  system  are  that  impurities  in  the  air  collect  mainly 
in  the  strata  near  the  floor,  that  it  is  much  easier  to  avoid  unpleasant 
draughts  and  the  entrance  of  dust  into  the  hall  when  the  air  passes 
out  through  the  floor  than  when  it  passes  in  through  it,  and  that  a 


CAPITOL    AT    WASHINGTON.  363 

more  uniform  distribution  of  the  incoming  air  with  less  interference 
with  the  transmission  of  sound  is  thus  secured.  The  first  of  these 
arguments  is  based  on  the  erroneous  idea  that  carbonic  acid  is  the 
dangerous  impurity  to  be  gotten  rid  of — and  that  it  accumulates  near 
the  floor  because  it  is  heavier  than  the  air.  The  other  reasons  given 
are  good  so  far  as  they  go — and  should  be  considered  in  connection 
with  the  arguments  in  favor  of  an  upward  system  for  a  large  hall,  the 
center  of  which  is  occupied  by  a  number  of  people.  These  arguments 
are  summed  up  in  the  following  extracts  from  Report  No.  119  of  the 
Documents  of  the  House  of  Representatives  of  the  second  session  of 
the  45th  Congress,  presented  in  1878  by  a  board  consisting  of  Pro- 
fessor Henry,  of  the  Smithsonian  Institution;  Colonel  Casey,  of  the 
U.  S.  Engineers;  Mr.  Clarke,  the  architect  of  the  Capitol;  Mr.  Schu- 
mann, C.  E.,  and  Dr.  J.  S.  Billings,  U.  S.  A.: 

"  The  problem  of  ventilation  of  the  hall  may  be  stated  as  follows:  How 
to  introduce  and  distribute  from  30,000  to  60,000  cubic  feet  of  fresh  air  per 
minute — corresponding  to  from  600  to  1,200  occupants — and  to  do  this  in  such 
a  way  that  the  occupants  shall  not  be  annoyed  by  heat,  cold,  or  currents  of 
air. 

"  Even  were  this  done,  perfect  ventilation  would  not  be  obtained,  for  this 
would  only  provide  for  dilution  of  the  impure  air,  while  in  perfect  ventilation 
the  impurities  are  not  so  diluted,  but  completely  removed  as  fast  as  formed, 
so  that  no  man  can  inspire  any  air  which  has  shortly  before  been  in  his  own 
lungs  or  in  those  of  his  neighbor. 

"  To  secure  such  ventilation  as  this,  horizontal  currents  must  be  avoided, 
and  all  the  air  in  the  room  should  be  made  to  move  directly  upward  or  directly 
downward.  It  is  utterly  impossible  to  thoroughly  ventilate  such  a  hall  as  that 
of  the  House,  if  fully  occupied,  by  any  so-called  natural  ventilation  by  means 
of  doors  and  windows. 

"The  relative  merits  of  the  upward  versus  the  downward  systems  of 
ventilation  in  large  halls  in  which  the  center  of  the  room  is  occupied  by  a 
number  of  people,  may  be  estimated  from  the  following  considerations: 

"First. — The  direction  of  the  currents  of  air  from  the  human  body  is, 
under  ordinary  circumstances,  upward,  owing  to  the  heat  of  the  body.  The 
velocity  of  these  currents  is  small,  but  it  may  be  estimated  as  being  certainly 
not  less  than  i  inch  per  second.  This  current  is  an  assistance  to  upward  and 
an  obstacle  to  downward  ventilation. 

"  Second. — The  heat  from  all  gas  flames  used  for  lighting  tends  to  assist 
upward  ventilation,  but  elaborate  arrangements  must  be  made  to  prevent  con- 
tamination of  the  air  by  the  lights,  if  the  downward  method  be  adopted. 

"  Third. — In  large  rooms  an  enormous  quantity  of  air  must  be  introduced 
in  the  downward  method,  if  the  occupants  are  to  breathe  pure  and  fresh  air. 
The  whole  body  of  air  in  the  room  must  be  made  to  move  uniformly  down- 
ward; for  if  at  any  point  this  be  not  the  case,  the  products  of  respiration  will 
rise  at  those  points,  and,  diffusing,  contaminate  the  air  which  is  coming  down 


364  CAPITOL    AT    WASHINGTON. 

to  be  breathed.  The  uniform  rate  of  descent  should  certainly  be  not  less  than 
3  inches  per  second,  in  order  to  overcome  the  ascensional  tendency  of  the 
currents  from  respiration,  the  heat  of  the  body,  etc.,  which  implies  that,  for 
every  100  square  feet  of  floor  area,  at  least  1,500  cubic  feet  of  fresh  air  are  to 
be  brought  in  per  minute.  As  the  floor  of  the  hall  and  galleries  of  the  House 
contain  12,927  square  feet.it  follows  that  the  amount  of  fresh  air  required 
would  be  193,500  cubic  feet  per  minute,  or  about  three  times  the  amount  which 
is  found  to  give  satisfactory  results  with  the  upward  method. 

"  Fourth. — In  halls  arranged  with  galleries  the  difficulty  of  so  arranging 
downward  currents  that  on  the  one  hand  the  air  rendered  impure  in  the 
galleries  shall  not  contaminate  that  which  is  descending  to  supply  the  main 
floor  below,  and,  on  the  other  hand,  the  supply  for  the  floor  shall  not  be  drawn 
aside  to  the  galleries,  is  so  great  that  it  is  almost  an  impossibility  to  effect  it. 

r"  For  these  and  other  reasons,  the  board  are  of  the  opinion  that  the  up- 
ward method  should  be  preferred.  In  the  upward  method  there  are  two  special 
difficulties  to  be  met  in  halls  of  this  kind.  The  first  is  dust  derived  mainly 
from  the  shoes  of  the  occupants.  This,  becoming  dry,  is  ground  into  fine 
powder,  some  of  which  is  kept  floating  in  the  air  by  the  upward  currents.  By 
careful  supervision,  and  by  the  use  of  carpets  which  can  be  easily  detached 
and  frequently  shaken,  as  is  done  in  the  English  House  of  Parliament,  this 
evil  can  be  so  much  mitigated  as  not  to  be  noticed. 

' '  The  second  difficulty  is  due  to  the  discomfort  produced  by  perceptible 
currents  of  air.  The  cause  of  this  is  insufficient  area  and  improper  position  of 
the  openings  for  the  admission  of  fresh  air.  If  the  area  of  openings  be  too 
small,  the  air  must  pass  through  them  with  too  great  velocity  in  order  to 
obtain  the  required  quantity.  In  a  hall  liable  to  be  so  fully  occupied  as  this, 
there  are  few  points  at  which  fresh-air  openings  can  be  placed  the  current 
from  which  will  not  impinge  on  some  part  of  the  body  of  some  occupant,  and 
if  it  does  so  impinge  the  velocity  should  not  exceed  2  feet  per  second,  in  order 
to  avoid  sensations  of  draught.  The  supply  of  air  for  the  House  should  be,  as 
we  have  seen,  from  600  to  1,200  cubic  feet  per  second,  whence  it  follows  that 
the  total  area  of  openings  should  be  nearly  500  square  feet.  It  is  desirable  to 
diminish  the  effect  of  these  openings  as  much  as  possible  by  placing  at  least  a 
part  of  them  at  points  where  the  currents  will  not  reach  a  person  for  several 
feet,  or  until  they  have  become  somewhat  diffused.  In  attempting  to  effect 
this  it  is  very  important  to  remember  the  law  of  the  adhesion  of  gases  to  sur- 
faces, and  it  is  from  omission  to  do  this  that  a  large  part  of  the  discomfort  of 
members  of  the  House  has  arisen.  It  should  be  distinctly  understood  that  the 
board  states  these  general  principles  only  as  applicable  to  large  assembly 
halls  where  a  number  of  people  are  gathered  in  the  center  of  the  room,  for 
under  other  circumstances  some  of  them  do  not  hold  good. " 

In  this  connection  the  report  made  in  1891  by  M.  Trelat  on  the 
ventilation  of  the  French  Chamber  of  Deputies  is  of  interest.  This 
chamber  is  much  overcrowded,  there  being  but  30  centimeters  square 
of  floor  space  to  each  deputy.  The  air  is  delivered  by  fan  propulsion 
at  the  ceiling  and  is  taken  out  at  the  floor,  giving  a  downward  system 


CAPITOL    AT    WASHINGTON. 


of  ventilation.  The  apparatus  is  powerful  enough  to  change  the 
air  in  the  chamber  every  six  minutes,  but  it  can  only  be  worked 
slowly,  owing  to  the  draughts  produced,  and  the  air  vitiated  by  respira- 
tion is  brought  back  to  be  reinhaled.  M.  Trelat,  as.  the  result  of  his 
observations,  emphatically  condemns  downward  ventilation  for  a  hall 
of  this  kind,  and  advises  a  radical  change. 


FIG.  125.— PLAN   SHOWING   AIR  DUCTS,  ETC.,  IN   CONNECTION   WITH   HEAT- 
ING APPARATUS,  SOUTH  WING,  U.  S.  CAPITOL. 


A.— Main  fan  for  hall. 

B.— Small  fan  for  committee  rooms. 


G.— Evaporator  and  mixing  chamber. 
//".—Heating  coils. 


The  small  fan  B,  shown  in  Fig.  125,  was  originally  connected  with 
the  space  immediately  over  the  hall,  it  being  supposed  that  at  times 
the  wind  was  deflected  from  the  central  dome  in  such  a  way  as  to  blow 
down  through  the  louvered  openings  into  this  attic,  which  openings 


366 


CAPITOL    AT    WASHINGTON. 


were  the  only  means  provided  for  the  escape  of  foul  air.  The  result 
of  the  use  of  this  aspirating  fan,  in  addition  to  the  rarefaction  of  the 
air  produced  in  the  hall  by  the  force  of  the  aspirating  shaft  or  chim- 
ney, was  such  that  there  was  a  constant  tendency  for  air  to  flow  into 
the  hall  from  the  surrounding  corridors,  and  whenever  a  door  was 
opened  the  direction  of  the  current  through  it  was  always  inward. 
These  currents  had  such  strength  that  it  was  found  necessary  to  place 
screens  opposite  the  doors  to  break  their  force. 

This  aspirating  fan  is  now  connected  with  the  corridors,  as  shown 
in  the  figure,  and  the  result  has  been  very  satisfactory. 


Ve f4  rt  L AT  I O fJ 


FIG.  126.— TRANSVERSE  SECTION  THROUGH  SOUTH  WING,  U.  S.  CAPITOL. 

A.—  Main  hall.  C.—  Main  fresh-air  duct 

B. — Space  over  hall.  D. — Fresh-air  supply  to  galleries. 

E.—  Exhaust  fan. 


The  total  area  of  clear  opening  for  the  admission  of  fresh  air  on 
the  floor  of  the  hall  is  about  300  square  feet  and  in  the  galleries 
about  125  square  feet.  The  total  area  of  openings  in  the  ceiling 
for  the  discharge  of  foul  air  is  about  670  square  feet,  being  three 
times  as  much  as  is  necessary.  This  is,  however,  a  matter  of  minor 
importance,  since  the  amount  of  flow  is  practically  controlled  by  the 
louvers. 

Through  the  courtesy  of  Mr.  Lannan,  the  engineer  of  the  House, 
I  am  able  to  present  a  table  of  data  showing  the  working  of  the  ap- 
paratus during  the  month  of  February,  1892. 


CAPITOL    AT    WASHINGTON. 


367 


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Average  relative  humidity 
"  revolutions  of  fan 
11  volume  of  air  mov 


368 


CAPITOL    AT    WASHINGTON. 


PIG.  127. -SECTION  THROUGH  AIR  DUCTS  AND   HEATING  APPARATUS 
'OF  SOUTH  WING,  U.  S.  CAPITOL. 


A.— Cold-air  duct. 

^.—Heating  coil. 

C. — Mixing  chamber. 


D.— Fresh-air  shaft. 
E  —Evaporator. 
/?— Fresh-air  shaft. 


CAPITOL    AT    WASHINGTON.  369 

The  results  obtained  are  still  better  demonstrated  by  the  results 
of  some  air  analyses,  made  at  the  request  of  the  writer,  in  January, 
1880,  by  Dr.  Charles  Smart,  U.  S.  A.  After  the  House  had  been  in 
session  3^  hours,  with  250  persons  present  on  the  floor  and  300  in  the 
gallery,  the  proportion  of  carbonic  acid  present  in  the  air  at  the  level 
of  the  desks  was  found  to  be  7.67  parts  per  io,ooc. 

As  a  portion  of  this  carbonic  acid  was  derived  from  the  under- 
ground duct,  the  amount  of  carbonic  impurity  is  really  not  excessive. 
It  shows,  however,  that  the  distribution  of  the  fresh  air  in  the  hall  is 
not  as  prompt  and  uniform  as  it  should  be,  since  with  the  amount  of  air 
passing  into  and  out  of  the  hall,  and  the  number  of  persons  present, 
the  amount  of  carbonic  impurity  present  should  not  have  exceeded  6.3 
parts  per  10,000. 

The  hall  of  the  House  of  Representatives  is  a  room  139x93 
feet,  and  36  feet  high,  with  galleries  and  retiring  rooms  beneath  them, 
which  reduce  the  area  of  the  floor  to  113x67  feet.  This  room  is 
surrounded  by  corridors  and  committee  rooms,  so  that  all  its  walls  are 
internal  walls,  and  it  is  lighted  entirely  from  above  by  a  skylight  which 
extends  over  the  greater  part  of  the  hall.  Beneath  it  is  a  basement 
story,  20  feet  high,  and  beneath  this  again  is  the  cellar  or  crypt,  in 
which  the  ventilating  apparatus  is  placed.  The  plan  of  this  cellar  floor 
is  given  in  Fig.  125,  for  which,  as  well  as  for  the  other  illustrations  of 
the  hall,  I  am  indebted  to  the  courtesy  of  Mr.  Edward  Clarke,,  the 
architect  of  the  Capitol.  The  fresh-air  supply  is  taken  from  a  point 
on  the  lower  terrace  about  200  feet  from  the  building,  by  means  of  a 
low  tower  open  at  the  top  and  a  tunnel,  to  the  large  fan. 

The  fan  is  16  feet  in  diameter  and  was  intended  to  supply  at  60 
revolutions  per  minute  50,000  cubic  feet  of  air  against  a  resistance  of 
about  half  an  inch  of  water  column,  and  when  running  at  from  100  to 
120  revolutions  to  give  100,000  cubic  feet  of  air,  which  was  supposed 
to  be  the  maximum  amount  required. 

The  report  on  the  ventilation  of  the  Senate  Chamber,  contained 
in  Senate  Report  No.  880,  52d  Congress,  first  session,  presented  July 
5,  1892,  shows  that  the  chief  cause  of  complaint  of  the  Senators  is  not 
impurity  but  the  temperature,  which  is  usually  from  70°  to  71°  F., 
being  that  which  is  most  agreeable  to  the  majority  of  the  occupants. 
A  certain  number  would  prefer  67°  or  68°,  and  three  or  four  would  like 
75°,  and  thus  if  the  temperature  is  to  be  kept  uniform  there  will 
always  be  complaints.  It  would,  of  course,  be  possible  to  vary  the 
temperature  in  different  parts  of  the  chamber,  or  even  to  so  introduce 
the  air  that  each  Senator  could  regulate  the  temperature  in  his  own 


370 


ACOUSTICS    OF    ASSEMBLY    HALLS. 


immediate  vicinity  to  suit  himself,  but  this  would  be  expensive,  and 
would  injure  the  acoustic  properties  of  the  hall. 

It  has  been  shown  by  experiments  that  the  direction,  intensity  and 
form  of  sound  waves  are  modified  when  they  pass  through  currents  of 
air  of  varying  density,  so  as  to  produce  indistinctness  of  the  sound, 
even  if  it  is  loud  enough  to  be  heard.  If  the  direction  from  the  speaker 


FIG   128. 


towards  the  points  where  it  is  desirable  that  he  should  be  distinctly 
heard  nearly  coincides  with  the  direction  of  the  ventilating  air  currents, 
and  if  these  are  of  nearly  uniform  temperature,  the  audience  will  obtain 
the  best  results ;  but  if  the  sound  waves  have  to  cross  ascending  cur- 
rents of  air  of  a  different  temperature,  and  therefore  of  different 


AMPHITHEATER    OF    THE    SORBONNE.  371 

density  from  that  of  the  surrounding  air,  the  sound  will  be  made  more 
or  less  confused  and  indistinct.* 

If  the  position  of  the  speakers  in  the  hall  be  tolerably  uniform,  as 
is  the  case  in  churches  and  theaters,  the  direction  of  the  ventilating 
currents  can  be  arranged  without  much  difficulty  to  give  the  audience 
the  best  chance  of  hearing  them  distinctly,  but  in  such  legislative  halls 
as  those  of  the  Senate  and  House  of  Representatives,  where  it  is  the 
custom  that  each  speaker  speaks  from  any  part  of  the  floor  which  he 
may  happen  to  select — a  vertically  ascending  column  or  sheet  of  warm 
air  at  any  point  within  the  circle  of  seats  will  sometimes  prevent  the 
speaker  from  being  distinctly  heard  in  certain  parts  of  the  hall. 

From  a  report  made  by  M.  Tre*lat  in  1891  it  appears  that  the  ven- 
tilation of  the  French  Chamber  of  Deputies  is  in  a  more  unsatisfactory 
condition  than  that  of  the  English  or  American  National  Assembly 
Halls.  The  French  chamber  is  overcrowded,  the  fresh  air  is  delivered 
at  the  top  of  the  room,  and  the  currents  of  air  are  strong  and  varied 
causing  great  discomfort.  The  only  remedy  is  to  build  a  new  and 
larger  hall. 

Figure  128  shows  a  section  of  the  amphitheater  of  the  new  Paris 
Sorbonne,  containing  3,000  seats.  -A  is  the  fresh-air  inlet  ;  C,  one  of 
three  propelling  fans,  each  furnisfiing  20,000  cubic  meters  of  air  per 
hour.  D  is  a  furnace  in  which  a  portion  of  this  air  is  warmed  ;  F  F, 
cold-air  shafts  ;  gt  regulating  valves  ;  If  H,  mixing  chambers  ;  //, 
hot  pipes  to  counteract  cold  down-draught  from  the  wall  ;  /",  large 
central  lantern  for  foul-air  exit.  The  object  is  to  provide  for  each 
person  20  cubic  meters,  or  about  706  cubic  feet,  of  fresh  air  per  hour. 
This  is  less  than  half  the  amount  that  should  be  supplied. 

The  air  inlets  are  in  the  floor  under  every  seat  and  are  covered 
with  two  perforated  baffling  plates  of  iron  placed  about  an  inch  apart, 
and  intended  to  allow  the  air  to  enter  with  a  velocity  of  less  than  i 
foot  per  second.  The  outlets  measure  in  all  45  meters  square  ;  the 
final  outlet  shaft  has  an  area  of  about  150  square  feet.  The  apparatus 
was  provided  by  Geneste  and  Herscher,  and  the  idea  is  to  heat  the 
walls,  which  are  hollow.  About  an  hour  before  the  public  is  admitted 
the  temperature  of  the  whole  building  is  raised  to  over  140°  F.,  but 
about  15  minutes  before  the  entrance  of  the  audience  the  heat  is 
shut  off  and  cool  air  is  driven  in  by  the  fans.  Thus  the  audience 
have  warm  walls  and  surfaces  about  them  and  breathe  cool  air  in  ac- 
cordance with  the  ideas  of  M.  Trelat. 

*  See  effect  of  motion  of  air  in  an  auditorium  upon  its  acoustic  qualities, 
by  W.  W.  Jacques.  Jour.  Franklin  Inst.,  CVI.,  1878,  p.  390. 


372 


NEW    YORK    MUSIC    HALL. 


With  this  amphitheater  may  be  compared  the  New  York  Music 
Hall  founded  by  Andrew  Carnegie,  a  full  description  of  which,  with 
plans,  is  given  in  The  Engineering  Record  of  July  4,  1891,  and  Febru- 
ary 6,  1892.  The  main  concert  hall  has  a  seating  capacity  of  3,000, 
the  recital  hall  beneath  this  seats  1,200.  The  fresh  warmed  air  enters 
the  music  hall  through  numerous  perforations  in  or  near  the  ceiling, 


*! 


L.ODGE. 


'Register* 


duct, 


•J^> 


AUD  TORIUM 


ick   and    Iron  Floor. 


'A  /Bric^  a^d  I-rori  Fjpoy'. ,,,,,,^^* 

\          '/^/////////////////^^^  ';%%1J' 


fou7  a?i~  flue  . 


Ei 


RECITAL       HAL.L 


cftam&er  under  /W//  <f /*ft? 
^S&^^^ 

FIG.  i2Q. 


being  forced  in  by  two  y-foot  Sturtevant  blowers  which  draw  it  through 
heaters  of  i^-inch  pipe  containing  6,600  square  feet  of  heating  surface. 
Figure  129  is  a  general  vertical  section  of  the  main  building,  not 
to  scale  or  accurate  position,  but  intended  as  a  diagram  to  show  the 
distribution  of  fresh  air  and  the  withdrawal  of  foul  air  in  the  principal 


NEW    YORK    MUSIC    HALL. 


373 


rooms.  Detail  A  shows  the  method  of  supplying  extra  heat  and  air  to 
the  stage  through  perforations  in  the  horizontal  top  of  the  6-foot 
wainscoting  IV,  around  the  walls. 


FIG.  130. 


Figure  130  shows  the  heating,  cooling  and  blowing  plant.     A  is 
the  fresh-air  shaft  from  the  roof,  6x12  feet,  supplying  the  distributing 


374 


NEW    YORK    MUSIC    HALL. 


chamber  G.  In  warm  weather  ice  may  be  placed  in  the  racks  C  C  to 
cool  the  air.  The  blowers  B  B  draw  the  air  into  the  chambers  D  D 
through  the  steam  radiators  H  H '.  E  JS  are  the  engines  driving  the 
blowers,  and  F  is  the  main  air  duct  having  a  cross-section  of  30 
square  feet. 


ATtt-Jfc. 


FIG.  131. 


Figure  131  shows  the  bottom  of  the  fresh-air  shaft  A,  with  its  out- 
lets. O  O  are  the  ice-racks;  P  P,  iron  drip-pans.  S  S  are  waste-pipes  •„ 
D  D,  doors. 

Figure  132  is  a  perspective  view  from  7",  Fig.  130,  of  the  chamber 
Z>,  two  sides  of  which  are  composed  of  radiators  H  H.  U  is  the 
steam  supply  and  Fthe  drip  pipe. 

Figure  133  is  a  section  at  z  z  Fig.  130  showing  the  inlet  to  the  blower 
and  the  check  valve  F,  which  opens  with  the  blast  but  closes  against 


NEW    YORK    MUSIC    HALL. 


375 


back  pressure.  The  air  is  drawn  out  from  the  hall  by  a  separate  fan 
system,  being  taken  from  or  near  the  floor  levels,  and  carried  in  a  shaft 
to  the  roof  where  the  exhaust  fans  are  located.  It  will  be  seen  that  this 


FIG.  133. 

is  a  system  of  downward  ventilation,  the  efficiency  of  which  can  only  be 
maintained  by  a  considerable  expenditure  for  power. 


376 


LENOX    LYCEUM. 


Figure  134  is  a  plan  of  the  basement  of  the  Lenox  Lyceum  in  New 
York  City,  which  is  described  as  follows  in  The  Engineering  Record  of 
February  i,  1890: 

The  main  portion  of  the  building  is  circular  in  form,  and  is  almost 
wholly  taken  up  by  the  auditorium,  which  is  75  feet  high  and  135  feet 
in  diameter,  with  a  total  seating  capacity  for  2,300  persons.  The  din- 
ing-room in  the  basement  will  seat  800  persons.  Around  this  room 


BASEMENT  ?LAN, 


Fig.  134. 

are  arranged  the  overhead  fresh  warm  air  ducts  A  A,  branching  out 
right  and  left  from  an  8x4-foot  Sturtevant  blower  £.  Fresh  air  is 
taken  in  through  a  flue  in  the  south  wall,  having  a  sectional  area  of  20 
square  feet,  and  is  passed  over  a  large  steam  radiator  of  special  de- 
sign, being  finally  delivered  into  the  galvanized-iron  distributing  duct 


LENOX    LYCEUM.  377 

- 

The  entire  contents  of  the  auditorium  and  dining-room  amount  to 
900,000  cubic  feet,  and  the  blower  is  designed  to  effect  a  complete 
change  of  air  every  15  minutes.  Branch  pipes  run  from  the  main  hot- 
air  duct,  and  are  connected  to  a  series  of  gratings  placed  near  the  floor 
of  the  auditorium.  These  are  covered  with  perforated  zinc  plates 
through  which  the  flow  of  fresh  warm  air  is  brought  down  to  a  velocity 
so  low  that  there  is  no  possibility  of  draught.  Hot-air  flues  T^also  rise 
to  the  gallery  floor. 

The  hot-air  supply  for  the  dining-room  is  taken  from  the  same 
blower  through  the  duct  C  issuing  near  the  ceiling,  but  the  air  is 
heated  to  a  much  higher  temperature  than  that  entering  the  audito- 
rium, and  is  delivered  in  proportionately  smaller  volume.  The  higher 
temperature  is  secured  by  interposing  in  the  duct  C  a  separate  radia- 
tor as  shown.  This  air  supply  is  entirely  discontinued  when  a  proper 
temperature  has  once  been  secured  in  the  room. 

Regulation  of  the  temperature  is  effected  automatically  by  John- 
son electric  heat  regulators,  which  control  the  steam  supply  to  the  ra- 
diators in  the  fresh-air  flue  according  to  the  temperature  of  the  audi- 
torium and  of  the  air  entering  it.  One  of  the  regulators  also  controls 
the  large  lo-foot  ventilator  in  the  roof  of  the  auditorium,  by  which  a 
uniform  volume  of  fresh  air  is  delivered,  and  a  practically  fixed  tem- 
perature is  maintained  in  the  auditorium. 

A  thermostat,  or  electrical  thermometer,  is  placed  in  the  audito- 
rium, another  in  the  main  air  duct  near  the  fan,  each  capable  of  mak- 
ing electrical  connection  with  the  electro-pneumatic  valve,  which  shuts 
off  the  steam  supply  to  the  radiators  when  the  auditorium  becomes 
warm.  The  delivery  of  fresh  air  is  maintained,  although  at  a  reduced 
temperature,  and  to  prevent  the  air  from  falling  below  72  degrees,  no 
matter  what  temperature  the  air  in  the  room  may  be,  the  thermostat  in 
the  main  duct,  at  72  degrees,  permits  just  enough  steam  to  enter  the 
coils  to  rai«e  the  air  to  75  degrees,  when  the  steam  is  again  turned  off. 

But  should  the  temperature  of  the  auditorium  fall  below  70  de- 
grees, or  the  degree  at  which  the  thermostat  is  set,  the  auditorium 
thermostat  would  turn  on  steam  regardless  of  the  thermostat  in  duct, 
and  so  continue  to  control  the  steam  supply  until  the  temperature  in 
the  auditorium  rises  to  the  degree  required. 

Still  another  thermostat  in  the  auditorium  is  set  4  degrees  higher 
than  the  thermostat  which  controls  the  coils.  When  the  atmosphere 
in  auditorium  is  heated  to  the  degree  at  which  this  thermostat  is 
set  the  large  lo-foot  ventilator  is  opened,  permitting  the  heated  air 
to  escape. 


37^  LENOX    LYCEUM. 

The  volume  of  fresh  air  entering  the  building  is  capable  of  varia- 
tion by  increasing  or  diminishing  the  number  of  revolutions  of  the 
blower.  Ordinarily  the  speed  of  the  latter  is  100  turns  per  minute,  at 
which  the  capacity  of  the  blower  is  about  40,000  cubic  feet  of  air  per 
minute. 

For  the  purpose  of  ventilation  a  large  brick  duct  D  D,  was  built 
below  the  dining-room  floor,  encircling  the  room.  Branches  from  this 
lead  to  register  boxes  in  the  floor  at  various  points,  and  also  in  the 
kitchen,  and  the  foul  air  is  drawn  into  the  duct  and  discharged  into 
the  open  air  by  a  4x6-foot  Sturtevant  exhauster  £,  driven  by  a  10 
horse-power  vertical  engine.  This  exhauster  has  a  capacity  of  15,000 
cubic  feet  of  air  per  minute.  The  movement  of  the  air  will  always  be 
from  the  main  auditorium  to  the  dining-room,  thence  to  the  kitchen, 
and  finally  into  the  exhaust  duct.  Odors  from  the  kitchen  or  dining- 
room  are  thus  prevented  from  rising  to  the  main  auditorium.  Above 
the  urinals  in  the  toilet-room  an  exhaust  duct  G,  of  3-square  foot  sec- 
tion is  arranged,  having  small  openings  downward,  as  shown  by  dotted 
lines,  and  discharging  into  a  flue  leading  to  the  roof.  The  ventilation 
there  is  effected  by  natural  draught,  which  is  sufficiently  strong  to 
create  a  flow  of  air  into  the  toilet-room  from  the  adjoining  spaces  on 
opening  the  door. 

The  apparatus  is  designed  also  to  cool  the  building  in  warm 
weather.  For  this  purpose  a  tank  is  arranged  underneath  the  engine- 
room  to  hold  cold  water,  which  is  forced  through  the  radiator  in  the 
fresh-air  flue  by  a  small  circulating  pump. 


CHAPTER  XVI. 

THEATERS.  AIR  IN  MANCHESTER  THEATERS.  GRAND  OPERA  HOUSE 
IN  VIENNA.  OPERA  HOUSE  AT  FRANKFORT-ON-THE-MAIN.  METRO- 
POLITAN OPERA  HOUSE,  NEW  YORK.  MADISON  SQUARE  THEATER. 
ACADEMY  OF  MUSIC,  BALTIMORE.  PUEBLO  OPERA  HOUSE.  EMPIRE 
THEATER,  PHILADELPHIA. 

AS  a  rule,  theaters  have  insufficient  and  unsatisfactory  arrangements 
for  ventilation.  They  almost  invariably  become  overheated 
when  the  audience  is  large,  while  the  stage  is,  as  a  rule,  cold  and  ex- 
posed to  draughts.  The  difficulties  in  the  way  of  obtaining  satisfactory 
results  are  much  the  same  as  those  in  large  legislative  halls,  and  are  to 
be  overcome  by  much  the  same  methods. 

The  following  tables  showing  the  condition  of  the  air  in  the  prin- 
cipal theaters  in  Manchester,  taken  as  types  of  well-arranged  English 
theaters,  are  taken  from  a  paper  by  W.  H.  Collins,  in  the  Report  of  the 
British  Association  for  the  Advancement  of  Science,  1890,  p.  773. 

If  we  could  have  similar  reports  for  some  of  our  modern  theaters, 
such  as  are  described  m  this  chapter,  they  would  add  greatly  to  the 
limited  stock  of  reliable  information  on  this  subject. 

Samples  of  air  were  taken  at  stated  periods  during  the  perform- 
ances in  the  months  of  December,  1889,  and  January,  1890.  Duplicate 
samples  were  analyzed  in  all  cases,  and  samples  of  the  air  outside  the 
theater  were  taken  simultaneously  for  the  purpose  of  comparison. 
The  examination  of  the  samples  was  confined  to  the  estimation  of  (i) 
carbonic  acid  (by  Pettenkofer's  method);  (2)  organic  matter  (by  Car- 
nelley's  method,  and  (3)  micro-organisms  (by  Hesse's  method,  "  Mit- 
theilungen  aus  dem  kaiserlichen  Gesundheitsamte,"  ii.,  1892). 

The  results  are  contained  in  the  tables  given  on  pages  380  and 

381. 

Of  late  years  more  attention  has  been  paid  to  the  ventilation  of 
opera  houses  and  theaters  by  architects,  and  some  very  good  results 
have  been  obtained. 


38o 


GRAND    OPERA    HOUSE    IN    VIENNA. 


Probably  no  theater  in  the  world  excels  the  Grand  Opera  House 
in  Vienna  in  the  extent  and  completeness  of  the  special  arrangements 
for  securing  ventilation,  and  in  no  theater  of  the  same  size,  and  under 
similar  climatic  conditions,  have  better  results  been  obtained. 

The  heating  and  ventilation  of  this  building  were  arranged  by  Dr. 
Bohm,  the  medical  director  of  the  Hospital  Rudolfsstiftung,  in  Vienna. 


Tables  Showing  Condition  of  Air  in  Manchester  Theaters. 
A. — COMEDY  THEATER,  MANCHESTER. 


Place. 

Time. 

Temp. 
F. 

CO2  Per 

10,000. 

Organic 
Matter. 
Per  Cent. 

Bact. 

I  C.C. 

Molds 
Per  c.c. 

Total 
Micro- 
Organisms. 

Stalls 

P.   M. 

6  30 

C-2 

12    6 

14.  6 

6 

T.A 

4.Q 

Q  o 

71 

Q   6 

34   2 

2Q 

4.1 

7O 

Pit 

Q   4.O 

96 

II        ^ 

60  4 

36 

3Q 

7C 

IO    5 

IO'? 

11    U 

63.1 

69 

104 

173 

Gallery            .   .     . 

8  5 

90 

12    I 

49.O 

34 

2O 

C.A 

Q     C 

116 

12.6 

56.3 

45 

45 

9O 

r 

6.30 

36 

5-1 

16.6 

25-3 

63 

89 

9.0 

36 

5.o 

16.9 

26.9 

106 

140 

Peter    Street  out-! 

9.40 

37 

5.1 

16.6 

40.6 

64 

116 

side  the  theater,  j 

10.5 

37 

5-2 

I7.i 

109 

103 

214 

8.5 

36 

5-2 

26.9 

26 

4i 

73 

L 

9-15 

36 

5-3 

16.9 

26 

40 

66 

B. — THEATER  ROYAL,  MANCHESTER. 


Place. 

Time. 

Temp. 

F. 

CO,  Per 

10,000. 

Organic 
Matter. 
Per  Cent. 

Bact. 

I  C.C. 

Molds 
Per  c.c. 

Total 
Micro- 
Organisms. 

Pit      

P.  M. 

7  AC 

o 
6q 

12.6 

69   5 

60 

60 

1  20 

8   15 

IOO 

14.  1 

7O.O 

65 

69 

134 

Gallery  

8  30 

121 

16.9 

1015.0 

96 

1  06 

2O2 

9.30 

116 

16.5 

109  .,0 

97 

1  20 

217 

Circle  

9.30 

95 

12.3 

46.0 

29 

II 

4° 

IO   O 

QO 

113 

69.0 

36 

41 

77 

r 

7.45 

39 

4-9 

16.9 

26 

40 

66 

8.  is 

39 

4-9 

17.4 

3i 

36 

67 

Peter    Street  out.  I 

8.30 

36 

5.3 

17-9 

39 

30 

69 

side  the  theater.  ") 

9-30 

33} 

5-6 

26.9 

45 

60 

105 

9-3° 

33  ) 

IO.O 

35 

5-9 

63.6 

69 

IOO 

169 

OPERA    HOUSE    IN    VIENNA. 
C. — PRINCES  THEATER,  MANCHESTER. 


Place. 

Time. 

Temp. 
F. 

CO  a  Per 

10,000 

Organic 
Matter. 
Per  Cent. 

Bact. 

I  C.C. 

Molds 
Per  c.c. 

Total 
Micro- 
Organisms. 

Pit 

P.  M. 

7   d5 

67 

II    ^ 

60  * 

16 

26 

J.2 

Q  O 

I  O4. 

J-2      O 

106  o 

60 

A  7 

112 

Circle             

8  o 

77 

IO   9 

40  O 

4O 

6 

46 

IO.O 

90 

14.0 

109.0 

26 

90 

116 

Gallery         

7-45 

94 

14.6 

116.0 

60 

40 

IOO 

IO   O 

116 

17    1 

206  o 

14  -i 

c  i 

IQ4. 

r 

7-45 

39 

5.6 

16.5 

29 

6 

35 

9.0 

40 

5.o 

17.3 

2O 

9 

29 

Peter    Street   out-  ! 
side  the  theater,  ] 

8.0 

IO.O 

37 
32 

4-9 
4-6 

17.9 

16.9 

25 

6 

4i 
5i 

66 

57 

1 

7-45 

39 

5.1 

40.3 

15 

ii 

26 

I 

IO.O 

3o 

5.o 

40.9 

12 

14 

26 

The  plan  and  section  of  so  much  of  the  building  as  is  necessary 
to  show  the  ventilation  of  the  audience  hall  are  given  in  Figs.  135  and 
136.  The  letters  mark  the  same  features  in  each  figure  and  have  the 
following  meaning  : 


A. — Fresh-air  chamber. 
BCD  E.— Heating  chambers. 
G.—  Tubes  for  fresh  cold  air. 


//.—Foul-air  shaft. 

S.— Fresh-air  fan. 

U. — Foul-air  for  aspirating  fan. 


The  building  measures  397x299  feet,  and  the  theater  itself  will 
contain  about  2,700  persons.  The  ventilation  is  produced  and  regula- 
ted by  two  fans,  as  will  be  seen  on  the  plans — the  lower  one  for  pro- 
pulsion, the  upper  for  aspiration.  This  last  is  also  aided  by  the  heat 
produced  by  the  great  chandelier,  which  has  90  burners.  The  heat- 
ing is  effected  by  steam,  and  the  air  enters  the  hall  at  a  tempera- 
ture of  from  63  to  65  degrees  F.,  the  points  of  entrance  being  at  the 
floor  and  in  the  risers.  Each  gallery  and  compartment  of  the  theater, 
including  the  stage,  has  an  independent  supply  duct  and  independent 
means  of  heating,  so  that  the  amount  of  supply  and  the  temperature 
can  be  regulated  for  that  portion  irrespective  of  the  rest.  The  velocity 
of  entrance  of  the  air  is  between  i  and  2  feet  per  second.  The  lower 
fan  is  a  helix,  devised  by  Professor  Heger,  of  the  Polytechnic  School 
of  Vienna.  It  measures  TI^  feet  in  diameter  externally,  and  has  a 
capacity  of  3, 531,658  cubic  feet  of  air  per  hour,  the  ordinary  figure  being 
from  2, 825, 324  to  3,001,907  cubic  feet,  corresponding  to  1,059  cubic  feet 
per  head  per  hour  The  aspirating  fan,  in  the  upper  shaft,  is  a  simple 
helix,  and  is  of  little  use.  Both  fans  are  operated  by  an  engine  of  1 6  horse- 


382 


OPERA    HOUSE    IN    VIENNA. 


power.  There  are  two  fresh-air  shafts  of  supply,  each  being  19^x13 
feet.  From  these  the  air  passes  into  a  basement  chamber,  where  in  warm 
weather,  sprays  of  cold  water  are  made  to  play.  From  these  it  passes  to 
the  lower  fan,  the  air  duct  from  which  is  48^  square  feet  in  area. 
This  duct  passes  below  the  center  of  the  theater  into  a  large  space 
having  the  same  extent  as  the  main  hall.  The  space  is  divided  into 


FIG.  135. 

three  stories.  The  lower  story  is  divided  into  distinct  chambers,  cor- 
responding to  the  orchestra  chairs,  dress  circle,  the  galleries,  etc.  The 
second  stage  contains  the  heating  coils,  which  are  composed  of  59,058 
feet  of  tubing  of  i -inch  interior  diameter,  containing  steam  at  a  pressure 
of  five  atmospheres.  The  upper  story  is  the  mixing  chamber.  It  will 
be  seen  by  Fig.  136  that  the  fresh  air  may  pass  directly  from  the  lower 


OPERA    HOUSE    IN    VIENNA. 


383 


to  the  upper  floor,  or  mixing  chamber,  through  tubes  about  3  feet  in 
diameter,  without  passing  through  the  heating  coils  at  all.  These 
tubes  are  valved,  and  can  be  opened  or  closed  to  any  extent.  The  foul 
air  passes  out  through  the  shaft  shown  in  Fig.  136,  which  shaft  is  13^ 
feet  in  diameter.  The  floor  surface  occupied  by  spectators  is  14,608 
square  feet,  the  capacity  of  the  hall  is  388,482  cubic  feet,  and  the  com- 
bined area  of  the  fresh-air  inlets  into  this  hall  is  807  square  feet. 


FIG.  136. 

By  means  of  electricity  the  temperature  in  different  parts  of  the 
house  can  be  observed  in  a  central  office  of  control,  and  here  also  are 
levers  which  control  the  valves  which  regulate  the  air  supply,  both  hot 
and  cold. 

During  an  operatic  performance,  the  superintendent  of  heating 
and  ventilation  is  on  duty  in  this  office,  and  sees  that  all  parts  of  the 
house  receive  their  due  supply  of  fresh  air,  and  are  kept  at  a  proper 
temperature. 


3*4 


FRANKFORT    OPERA    HOUSE. 


In  connection  with  the  heating  and  ventilating  arrangements  of 
the  Vienna  Opera  House  should  be  mentioned  those  of  the  new  Opera 
House  in  Frankfort-on-the-Main,  which  are  arranged  upon  essentially 
the  same  system,  although  with  improvement  as  to  details,  more  es- 


FIG.  137— METROPOLITAN  OPERA  HOUSE,  NEW  YORK  CITY.— GROUND  FLAX 

pecially  as  regards  the  supply  of  air  to  the  galleries.  The  apparatus 
in  this  building  is  designed  to  supply  warmed  and  moistened  air 
sufficient  for  2,000  persons.  The  warming  is  effected  by  steam, 


FRANKFORT    OPERA    HOUSE. 


the  boilers  for  this  purpose  being  in  the  cellar  of  a  building  placed  on 
the  opposite  side  of  the  street  and  connected  with  the  opera  house  by 


FIG.  i38.-METROPOLITAN  OPERA  HOUSE,  NEW  YORK  CITY. 
LONGITUDINAL  SECTION. 

means  of  a  tunnel  passing  beneath  the  pavement.     There  are  two  of 
these  boilers,  each  having  about  540  square  feet  heating  surface,  and 


386  METROPOLITAN    OPERA    HOUSE. 

supplying  steam  at  from  six  to  nine  pounds  pressure.  The  radiators  in 
the  heating  chamber  beneath  the  audience  hall  and  stage  are  the  usual 
pipe  radiators,  and  furnish  10,800  square  feet  of  radiating  surface,  two- 
fifths  of  which  is  devoted  to  the  stage  and  adjoining  rooms. 

The  fan  for  propelling  the  fresh-air  supply  is  a  helix,  9^/2 
feet  in  diameter,  of  the  same  pattern  as  that  used  in  the  Vienna 
Opera  House,  and  it  furnishes  in  winter  2,800,000  cubic  feet  of  air  per 
hour,  or  1,400  cubic  feet  per  person,  being  an  increase  over  the  amount 
allowed  in  Vienna.  The  maximum  capacity  of  the  fan  gives  about 
2,400  feet  per  head  per  hour,  and  this  is  intended  to  be  the  summer 
supply.  Provision  is  made  at  the  point  of  entrance  of  the  fresh  air 
into  the  building  for  cleansing,  moistening  and  cooling  it  by  drawing  it 
through  sprays  of  water. 

The  general  results  obtained  by  the  apparatus  are  very  good,  and 
are  especially  well  marked  in  hot  weather,  when  a  good  audience  can 
always  be  collected  in  this  building,  because  of  its  coolness,  freshness 
and  comfort. 

The  Metropolitan  Opera  House,  in  New  York  City,  recently 
burned,  was  another  large  building  of  this  class  in  which  excellent 
results  were  secured,  so  far  as  heating  and  ventilation  are  concerned. 
The  apparatus  in  this  case  was  devised  by  Mr.  Frederic  Tudor,  and  is 
described  in  The  Sanitary  Engineer  of  December  6  and  13,  1883. 

The  principle  involved  was  "  plenum  ventilation, "the  object  being 
to  have  a  pressure  within  the  building  slightly  in  excess  of  that  of  the  air 
without  the  walls,  so  as  to  insure  an  outward  current  through  crevices  of 
doors  or  windows  or  through  accidental  openings.  To  this  end  the 
shaft  (at  the  right  of  the  stage  on  the  ground  plan)  7'xio'6"  (73.5  square 
feet),  was  provided  in  connection  with  the  fan,/.  Air  was  taken  in  at  a 
height  of  75  feet  from  the  ground,  and  60  feet  below  the  top  of  the  boiler 
chimney,  and  as  remote  therefrom  as  possible.  The  air  drawn  down 
through  the  shaft  entered  a  settling  chamber,  48x20  feet,  with  a  height 
of  10  feet,  and  thence  it  was  drawn  through  the  heating  coils  C  C,  or 
passed  around  through  the  swinging  doors,  as  shown,  to  the  fan. 
From  the  fan  the  general  course  of  the  air  is  through  the  main  air 
duct,  between  the  walls  A  and  B  in  the  basement  in  the  direction  of 
the  arrows,  but  all  the  basement  within  the  walls  A  A  is  subject  to 
the  same  pressure.  From  the  basement  room  immediately  under  the 
auditorium  floor  the  air  was  admitted  through  many  4X4-inch  openings 
made  through  the  brick  arches  into  the  space  between  the  arches  and 
the  floor.  From  this  space  the  air  for  the  occupants  of  the  parquet 
chairs  passed  through  the  risers  of  the  floor  steps  on  which  the  chairs 


METROPOLITAN    OPERA    HOUSE. 


38? 


were  set.  In  these  risers  were  openings  continuous  at  their  face,  but 
of  peculiar  construction,  and  covered  with  No.  16  galvanized  iron  per- 
forated with  y^-inch  holes. 

The  air  which  supplied  the  boxes  was  carried  from  the  main  air 


FIG.  139.— METROPOLITAN    OPERA    HOUSE,    NEW    YORK   CITY.— TRANSVERSE 

SECTION. 

duct  in  the  flues  in  the  wall  A  to  the  spaces  between  the  floors  and 
ceilings,  as  shown  on  transverse  section,  and  discharged  at  the  edges 
of  the  tiers  at  a  a.  Its  course  was  then  upward  and  backward,  to  the 
flues  in  the  wall  B>  which  had  an  exhausting  power  derived  from  the 


388  METROPOLITAN    OPERA    HOUSE. 

heat  of  the  gas-jets  under  the  hoods  in  the  balcony  and  family  circle, 
and  from  the  gas-light,  when  used,  in  the  private  parlor,  immediately 
behind  the  chairs,  a  detail  of  which  is  shown  in  Fig.  139.  The  balcony 
and  family  circle  received  air  through  the  large  flues  G  G  at  the  ends 
of  the  main  air  ducts  in  the  proscenium  wall  and  through  the  flues 
G  G  and  H  in  the  wall  A. 

"  The  air  was  discharged  into  the  spaces  shown,  formed  by  the  ceil- 
ings of  the  box  parlors  on  the  second  tier  and  by  the  ceiling  in  the 
angle  of  the  balcony  at  the  walls.  It  was  then  distributed  to  the  edge 
of  the  balcony  and  family  circle  at  a  a  and  through  a  2X4-inch  hole  at 
the  back  of  every  chair  in  the  risers  of  the  galleries. 

"  The  outlets  for  foul  air  were  those  already  mentioned  in  the 
boxes,  and  shown  in  the  wall  B  (ground  plan),  and  those  in  the  pros- 
cenium wall  at  the  ends  of  the  gallery  and  balcony. 

"  In  the  highest  part  of  the  gallery  ceiling,  in  the  rear,  were  five 
registers,  under  two  of  which  there  were  clusters  of  gas  brackets,  the 
aggregate  area  being  20  square  feet.  In  the  balcony  ceiling  there 
were  likewise  four  registers  of  15  square  feet,  under  each  of  which 
there  was  a  cluster  of  gas  brackets.  The  foul  air  from  these  was  like- 
wise carried  to  the  wall  B  in  galvanized  ducts. 

"  In  the  center  of  the  dome-shaped  ceiling  was  the  main  con- 
trolling valve  to  the  ventilation.  It  was  circular,  16  feet  in  diameter, 
and  admitted  of  adjustment  by  the  raising  and  lowering  of  the  bell- 
shaped  disk  by  the  winch  shown  in  the  longitudinal  section. 

"By  the  adjustment  of  this  valve,  the  pressure  within  the  house 
could  be  regulated  and  the  condition  of  plenum  maintained  under 
varying  conditions  of  the  speed  of  the  fan  made  necessary  by  climatic 
changes. 

"  All  the  foul-air  outlets  in  front  of  the  proscenium  wall  opened 
into  the  space  between  the  ceiling  and  the  roof,  and  reached  the  out- 
side atmosphere  through  the  louvered  ventilator  at  the  apex  of  the  roof. 
This  ventilator  had  openings 'equal  to  108  square  feet,  with  an  inner 
shield  to  prevent  the  admission  of  snow  or  rain. 

"  The  stage  had  separate  ventilators  at  the  roof  and  in  the  side 
walls,  and  was  warmed  by  direct-radiation  coils  on  the  back  wall.  By 
this  means  a  difference  of  pressure  is  kept  between  the  house  and  the 
stage  when  the  curtain  is  down;  enough  to  belly  the  latter  slightly 
toward  the  stage.  The  rising  of  the  curtain  then  allows  air  to  pass 
from  the  house  to  the  stage  ventilators. 

"  In  the  coil  chamber,  between  the  coils  C  C  and  the  fan  was 
placed  an  evaporating  fan,  to  regulate  the  hygrometric  state  of  the  in- 


METROPOLITAN    OPERA    HOUSE. 


3*9 


coming  air.  The  difference  of  temperature  between  a  dry  and  wet 
bulb  thermometer,  in  the  main  air  duct,  was  maintained  at  from 
14  to  1 6  degrees. 

"  To  regulate  the  hygrometric  state  of  air  after  it  left  the  coils, 
the  evaporating  pan  (marked  Pan,  on  the  ground  plan),  a  detail  of 
which  is  shown  in  Fig.  140,  was  devised.  The  pan  proper  was  of  iron, 
4x12  feet,  and  12  inches  deep.  Within  the  pan  was  a  brass  coil  of 
i -inch  pipes,  #.  This  coil  had  a  steep  incline,  as  shown  in  the  section, 


FIG.  140. 

Fig.  141.  The  elbow  of  each  inclined  pipe  was  at  the  level  of  the  top 
of  the  overflow  pipe,  but  the  other  end  rested  on  the  bottom  of  the 
pan.  By  raising  or  lowering  the  water  in  the  pan,  more  or  less  of  the 
coil  was  submerged,  and  more  or  less  moisture  driven  off  into  the  air. 
"Figure  141  is  a  detail  of  the  manner  of  admitting  air  through 
the  auditorium  floor.  The  arches  were  of  brick,  and  the  whole  space 
between  them  and  the  wooden  floor  was  filled  with  warmed  air,  which 
entered  through  a  baffle  a,  that  ran  the  whole  length  of  the  steps. 


"Figure  142  is  a  section  and  plan  of  the  private  boxes,  of  which 
there  were  120.  The  air  was  carried  through  the  floors  from  the  flues 
in  the  wall  A,  and  delivered  at  the  edges  of  the  box  balconies,  as 
shown. 

"Figure  143  represents  the  special  ventilation  of  the  footlights. 
At  the  edge  of  the  stage  at  S,  on  the  ground  plan,  was  a  system  of 
flues  connecting  with  the  exhaust  fan  J?, 


390 


METROPOLITAN    OPERA    HOUSE. 


"  The  section  is  through  one  of  n  short  flues,  8x12  inches,  which 
connected  the  space  formed  by  the  metal  reflector  and  the  metal  edge 
of  the  stage,  with  a  main  or  trunk  flue,  which  in  turn  connects  with 
the  fan.  This  space,  within  which  the  three  gas  pipes  for  the  different 
colored  lights  lie,  was  divided  into  as  many  sections  as  there  were 


SECTION!  THROUGH  PRIVATE  BOX 


FIG.  142. 

branch  flues,  and  within  each  flue  was  a  damper  d.  These  dampers 
were  set  and  fixed  with  the  use  of  a  water  gauge,  so  as  to  give  a  differ- 
ence of  pressure  in  each  flue  of  one-half  inch  water  pressure,  the 
object  being  to  get  an  equal  pressure  of  draught  into  all  the  openings 
at  the  edge  of  the  reflectors,  over  the  gas  chimneys. 


MADISON    SQUARE    THEATER. 


391 


u  The  main  fan  was  1 2  feet  6  inches  in  diameter  by  45  inches  in 
the  width  of  the  blades,  and  delivered  about  70,000  cubic  feet  of  air 
per  minute  at  100  revolutions  per  minute." 

Another  theater  in  New  York,  in  which  special  attention  has  been 
given  to  ventilation,  is  the  Madison  Square  Theater,  a  good  descrip- 
tion of  which,  prepared  by  Mr.  W.  G.  Elliott,  was  published  in  The 
Sanitary  Engineer  for  October  15,  1880.  From  this  description  I  take 
the  following  extract: 

"  From  near  the  rear  end  of  the  gable  a  square  wooden  cupola 
rises  to  a  height  of  about  20  feet  above  the  roof.  Each  side  of  this  is 
provided  with  two  sliding  shutters  operated  by  ropes  from  below. 
These  openings  face  the  cardinal  points  of  the  compass  and  are  used 
in  pairs;  thus,  if  the  wind  is  southwest,  the  shutters  at  the  south  and 


west  are  opened  while  the  others  remain  closed.  The  shaft  into  which 
these  open  is  square,  6  feet  in  section,  and  extends  downward  behind 
the  scenes  to  the  cellar. 

"  This  inlet  shaft,  as  well  as  many  of  the  larger  ducts,  is  con- 
structed of  smoothed  pine  boards,  sheathed  in  places  with  paper,  and 
having  few  bends. 

"  Suspended  in  it,  point  downward,  is  a  conical-shaped  cheese- 
cloth bag,  about  40  feet  deep,  through  which  the  incoming  air  is 
filtered.  A  chamber  at  the  bottom  of  the  inlet  is  provided  with  a 
number  of  shelves  inclined  at  an  angle  of  about  45  degrees,  upon 
which,  in  summer,  ice  is  placed  to  chill  the  air.  From  this  point,  the 
main  duct,  diminished  to  a  diameter  of  4  feet,  connects  at  the  axis 
with  a  Sturtevant  fan,  8  feet  in  diameter,  with  blades  3  feet  by  18 


392  MADISON    SQUARE    THEATER. 

inches,  and  making  150  revolutions  per  minute.  The  periphery  of 
this  wheel,  moving  at  the  rate  of  about  two-thirds  of  a  mile  per  minute, 
forces  the  air  at  a  high  velocity  into  the  delivery  duct,  5x3  feet,  in 
which  is  placed  another  mass  of  ice.  Four  tons  are  used  every  night, 
two  in  the  delivery  and  two  in  the  inlet  duct. 

"  The  delivery  duct  is  of  brick,  and  is  branched  into  six  sheet-iron 
pipes,  each  2  feet  in  diameter.  Two  of  these  are  again  subdivided  in 
two,  and  open  into  four  brick  chambers,  4  feet  square.  Three  steam 
radiators  are  placed  in  each  chamber  to  supply  heat  in  winter. 

"  The  auditorium  is  divided  into  four  sections  of  90  seats  each, 
and  every  individual  seat  is  supplied  from  the  chambers  by  4-inch  tin 
pipes,  90  of  which  are  connected  with  each  chamber. 

"  Two  of  the  2-feet  flues  from  the  main  brick  delivery  duct  have 
not  yet  been  accounted  for.  Each  of  them  is  subdivided  into  three 
smaller  sheet-iron  flues,  one  set  passing  up  the  side  wall  on  the 
right  and  the  other  on  the  left  of  the  house,  and  opening  into  the 
auditorium  through  several  4Xio-inch  orifices  just  beneath  the  first 
balcony,  10  feet  above  the  floor,  and  also  through  a  number  of  2- 
inch  openings  in  the  lower  edge  of  the  balcony,  and  also  across  the 
entire  front  of  the  stage. 

"  Through  the  former  openings  in  summer  the  cooled  air  is  poured 
into  the  house  to  reduce  the  temperature  and  to  furnish  a  supply  for 
respiration. 

"  The  dome  chandelier,  together  with  each  wall  bracket,  are  en- 
cased in  glass,  and  pass  the  products  of  combustion  into  separate  flues 
connected  with  the  exhaust  fan.  The  proscenium  boxes  and  the  ele- 
vated orchestra  chamber  have  their  separate  inlets  and  outlets,  while 
the  galleries  are  as  well  supplied  as  the  parquet. 

"  Another  Sturtevant  blower,  8  feet  in  diameter,  located  upon  the 
roof  near  the  middle  of  the  building,  is  employed  to  exhaust  the  foul  air. 

"  A  wooden  flue,  4x5  feet,  descends  from  this  at  a  sharp  incline 
to  the  floor  of  the  attic,  there  dividing  at  right  angles  into  two  smaller 
ducts  3  feet  square.  These  are  again  subdivided  in  two,  24  inches 
square.  Two  of  them  withdraw  foul  air  through  six  6-inch  pipes  in 
the  ceiling  under  both  sides  of  the  first  balcony. 

"  The  two  others  pass  down  to  the  lobby,  opening  into  two  20x24- 
inch  registers  in  the  wall,  and  located  near  the  floor  on  each  side  of 
the  main  entrance. 

"  An  additional  register,  5  feet  in  diameter,  is  placed  in  the  ceil- 
ing at  the  rear  of  the  upper  balcony,  and  connected  by  means  of  a 
large  flue  with  the  main  exhaust  duct." 


BALTIMORE    ACADEMY    OF    MUSIC.  393 

Another  older  building  of  this  class  which  is  worthy  of  note  in 
this  connection  is  the  Academy  of  Music,  in  Baltimore.  In  this  build- 
ing the  special  object  of  the  architects  seems  to  have  been  to  make  the 
method  of  ventilation  serve  also  to  improve  the  acoustic  effects,  or,  at 
all  events,  not  to  interfere  with  them.  To  this  end  it  is  desirable  that 
the  sound  of  the  actor's  voice  shall,  as  far  as  possible,  go  with  the  main 
current  of  air  rather  than  across  or  against  it.  For  this  purpose  they 
bring  the  supply  of  air  for  the  audience  mainly  from  the  stage,  warming 
it  when  necessary  by  means  of  ordinary  steam  coils.  Before  the  audi- 
ence assembles  the  hall  is  warmed  by  hot  air  admitted  through  two 
openings  in  the  parquet,  which  openings  are  usually  closed  before  the 
performance  commences.  The  exit  of  foul  air  is  intended  to  be  by  a 
large  shaft  from  the  center  of  the  ceiling,  the  opening  of  which  is  con- 
trolled by  a  valve.  To  secure  distribution  of  the  air,  large  exhaust 
flues  are  placed  in  the  walls,  opening  below  in  the  rear  of  the  galleries 
and  communicating  above  with  the  exhaust  shaft  above  referred  to. 
A  sketch  of  the  arrangement  is  given  by  Mr.  Neilson,one  of  the  archi- 
tects of  the  building,  in  the  second  biennial  report  of  the  State  Board 
of  Health  of  Maryland,  printed  in  1878. 

The  acoustic  properties  of  this  theater  are  excellent,  and  the  sup- 
ply of  air  to  the  galleries  is  fairly  good.  The  only  force  available  for 
securing  change  of  air  for  the  seats  on  the  lower  floor  is  practically  the 
heat  furnished  by  the  audience  themselves,  the  supply  of  air  being  in- 
sufficient, and  the  great  mass  of  the  fresh  incoming  air  curving  upward 
as  it  enters  from  the  stage.  An  objection  to  this  direction  of  the  main 
current  is,  that  in  case  of  fire  the  direction  of  the  draught  would  be 
from  the  stage,  with  its  mass  of  highly  combustible  material,  toward 
the  audience,  so  that  the  mass  of  smoke  and  flame  would  be  whirled 
directly  among  the  people. 

The  heating  and  ventilation  of  the  Pueblo  Opera  House,  at 
Pueblo,  Col.,  are  described  and  illustrated  in  The  Engineering  Record 
of  May  23  and  May  30,  1891,  from  which  the  following  summary  is 
taken: 

Figure  144  is  a  ground  floor  plan  of  the  building. 

Figure  145  is  a  plan  of  the  second  floor,  the  third  and  fourth 
floors  being  substantially  the  same. 

Figure  146  is  a  section  of  the  stage  and  auditorium. 

The  main  fresh-air  duct  A,  from  the  propelling  fan,  is  54  inches 
in  diameter,  and  is  made  of  galvanized  iron.  Its  branches  carry  air 
to  the  registers  F  G  H.  O  O  are  direct  radiators,  and  R  R  are  open- 
ings into  the  foul-air  shaft  Z. 


394 


PUEBLO    OPERA    HOUSE. 


FIG. 


^.—Property  room. 

D.  -Office. 

^.—Vestibule. 

F.— Lobby. 

K. — Dressing  room. 

N. — Toilet  room. 


-S1.— Stores. 

A.— Ventilating  shaft. 

H H.—  Registers,  3x4  feet. 

Z.  L. — Registers  from  hot-air  flues. 

C  C. — Openings  into  foul-air  flues. 

g  h  t\  etc. — Direct  radiators. 


PUEBLO    OPERA    HOUSE. 


395 


FIG.  145. 

O.— Offices. 

PP  U. — Card  rooms.  Y. — Skylights  from  first-floor  roof. 

The  small  letters  indicate  direct  radiators. 


O. — Billiard  room. 
Y.-i 


396 


PUEBLO    OPERA    HOUSE. 


FIG.  146. 


PUEBLO  OPERA  HOUSE. 


397 


Figure  147  is  a  diagram  plan  of  the  air  ducts. 

Figure  148  is  a  plan  of  the  fan  chamber  Fand  coil  room  Xm  the 
second  story  of  the  boiler  house.  Figure  149  is  an  elevation  at  /,  Z, 
Fig.  148.  B  is  a  7-foot  Sturtevant  fan  driven  by  the  engine  JEt  and 
discharging  blast  through  the  54-inch  conduit  A. 


1    I     1    1 

G  G 


FIG.  147. 


At  C  are  the  1  2  heater  coils,  each  eight  pipes  high,  eight  pipes  wide, 
and  7  feet  6  inches  long,  supported  on  a*  pipe  frame  Z.  W  W,  etc., 
are  counterweights  balancing  valve  door  N,  which  is  operated  by  cord 
.//from  the  engine  room.  Door  N  does  not  quite  cover  the  whole 
opening  in  the  partition  P.  When  fully  raised,  as  here  shown,  a  lower 


PUEBLO    OPERA    HOUSE. 


space  O  is  left,  through  which  the  fan  draws  air,  which  has  entered  at 
My  and  passing  through  the  coils  C  has  been  slightly  tempered  and  is 
delivered,  comparatively  cool,  in  duct  A.  If  the  door  N  is  dropped 
to  the  floor  the  inlet  is  closed  at  Oy  and  another  one  is  opened  at  (?, 
from  which  the  hottest  air  in  chamber  X  is  admitted  to  Y.  Interme 


FIG.  148. 


FIG.  149. 


diate  positions  of  door  JV  enable  the  introduction  of  hot  and  tempered 
air  in  any  desired  proportions.  6"  6"  are  entrance  doors  to  the  cham- 
bers; Tis  the  smoke-stack;  T^and  G  are  steam  and  exhaust  pipes  to 
engine  E\  I  is  a  steam  pipe  to  radiator  coils. 


EMPIRE    THEATER,    PHILADELPHIA. 


399 


The  heating  and  ventilating  system  was  designed  and  installed  by 
the  L.  H.  Prentice  Company,  of  Chicago,  111.  Adler  &  Sullivan,  of 
Chicago,  were  the  architects. 

Figures  150  and  151  show  in  a  floor  plan  and  section  the  arrange- 
ments for  heating  and  ventilation  of  the  Empire  Theater  in  Philadel- 


1 1 1 1 1 

FIG.  150.— EMPIRE  THEATER.— FLOOR  PLAN. 


A.— Fresh-air  chamber. 

H, — Heating  coils. 

D.— Delivery  ducts  for  fresh  air. 

H  R.— Hall  registers. 

z'z'z'and  c  c.—  Air  inlets  to  dressing  rooms. 


d  d  d,— Dampers. 


^.—Blower. 

//. — Fresh-air  inlet. 

R.  —Delivery  registers. 

P  P  P.— Passageway  beneath  auditorium. 

ooo  and  c  c,— Air  outlets  from  dressing  rooms. 


phia,  as  provided  by  the  Philadelphia  Steam  Engineering  Company. 
The  total  space  in  the  building  is  546,223  cubic  feet,  of  which  277,375 
are  in  the  auditorium  and  211,370  in  the  stages. 


400 


EMPIRE    THEATER,    PHILADELPHIA. 


It  is  a  hot-blast  system,  the  fan  being  7  feet  in  diameter,  with  an 
inlet  45  inches  in  diameter  and  rotating  250  times  per  minute.  The 
heating  coil  contains  6,000  feet  of  i-inch  pipe  arranged  in  eight  inde- 
pendent sections. 

The  velocity  in  the  main  duct  is  intended  to  be  20  feet  per  second, 
and  in  the  side  wall  flues  10  feet  per  second.  The  area  of  the  flues 
for  the  auditorium  is  19.75  square  feet,  and  the  registers  have  two  and 
a  half  times  the  area  of  the  flues.  There  are  20  of  these  placed  8  feet 
above  the  floor,  and  the  air  is  supposed  to  pass  through  them  with  a 
velocity  of  10  feet  per  second,  which  would  give  a  quantity  sufficient 
to  renew  the  air  in  the  room  once  in  15  minutes. 


FIG.  151.— EMPIRE  THEATER. -VERTICAL  SECTION. 


B.— Blower. 

D.— Delivery  ducts. 

^.—Delivery  registers. 


V.—  Outlets  for  air. 

V  S.— Ventilating  duct  for  dressing  rooms. 


The  area  of  the  ducts  for  the  stage  is  8.75  square  feet.  The  area 
of  stage  registers  about  20  square  feet.  These  registers  are  in  the 
floor. 

The  outlet  is  from  the  ceiling  of  the  auditorium  through  16  open- 
ings, each  18x24  inches,  into  the  loft  which  is  surmounted  by  a  large 
louvered  shaft  opening  to  the  outer  air.  The  dressing  rooms,  smoking 
room,  etc.,  have  separate  ventilation. 

The  Royal  Theater,  of  Copenhagen,  built  in  1872-74,  seats  about 
1,750  persons,  is  heated  by  steam,  and  is  ventilated  by  upward  currents, 


GENEVA    THEATER.  401 

the  air  being  brought  in  below  the  seats  and  taken  out  above.     The 
supply  of  air  is  arranged  for  546  cubic  feet  per  second. 

The  central  heating  chamber  contains  two  heating  coils  which 
may  be  used  separately  or  together;  one  has  1,028  and  the  other  2,056 
square  feet  of  radiating  surface.  The  air  is  introduced  into  the  hall 
with  a  velocity  of  i  foot  per  second.  Above  the  central  heating 
chamber  is  a  mixing  chamber  into  which  cool  air  may  be  brought  from 
without  to  keep  the  temperature  of  the  mixture  at  66°  F.,  this  being 
obtained  by  an  automatic  electric  regulating  apparatus.  The  stage  is 
warmed  by  direct  radiators. 

In  the  Lessing  Theater,  at  Berlin,  the  air  to  the  auditorium  is  de- 
livered beneath  the  seats,  and  1,410  cubic  feet  per  person  per  hour  are 
allowed,  entering  at  a  velocity  of  1.3  feet  per  second. 

In  the  new  theater  at  Prague  1,620  cubic  feet  of  air  are  furnished 
per  person  per  hour,  and  both  a  propelling  and  an  exhaust  fan  are  used. 

In  the  Geneva  theater,  which  is  intended  for  1,300  spectators,  the 
air  is  drawn  through  the  heating  chambers  and  forced  by  fans  into  the 
auditorium  through  about  400  short  vertical  flues  provided  with  sliding 
dampers  and  covered  with  perforated  sheets  of  metal  at  their  outlets 
which  are  beneath  the  seats.  Other  flues  convey  a  portion  of  the  air 
to  the  hollow  floor  of  the  first  tier  of  boxes  from  which  it  escapes  into 
the  auditorium  at  a  height  of  about  8  feet.  The  supply  of  air  fur- 
nished by  the  fans  to  the  auditorium  and  corridors  is  about  800,000 
cubic  feet  per  hour.  The  temperature  of  the  upper  gallery  is  about 
5°  F.  higher  than  that  of  the  pit.  Exhaust  fans  draw  the  air  through 
openings  near  the  floors  of  the  pit  and  of  the  first  and  second  galleries. 
The  general  result  is  reported  to  be  good. 

The  theater  at  Nice  is  ventilated  in  much  the  same  manner,  the 
allowance  of  air  per  head  being  said  to  be  about  316  cubic  feet  per 
hour  in  winter,  and  421  cubic  feet  in  summer.  Either  the  air  supply 
must  be  much  greater  than  this  or  the  air  must  become  very  foul  when 
the  theater  is  crowded. 


CHAPTER  XVII. 

CHURCHES. 

AS  a  rule  churches  are  like  theaters  in  having  insufficient  and  un- 
satisfactory arrangements  for  ventilation.  There  are,  however, 
a  few  exceptions,  and  one  of  these  is  the  Fifth  Avenue  Presbyterian 
Church,  of  New  York  City,  commonly  known  as  Dr.  Hall's  Church, 
which  has  been  specially  commended  for  its  ventilation  by  competent 
judges,  and,  among  others,  by  Captain  Galton,  who  speaks  of  it  as 
the  best  ventilated  church  he  has  seen. 

I  am  indebted  to  the  architect,  Mr.  Carl  Pfeiffer,  of  New  York, 
for  the  data  and  drawings,  Figs.  152,  153,  used  in  the  following 
description: 

This  church  covers  an  area  of  100x200  feet,  and  the  auditorium 
is  100  feet  deep  on  the  main  floor,  136  feet  deep  on  the  gallery,  85  feet 
wide,  with  a  ceiling  60  feet  high,  and  is  intended  to  furnish  comfortable 
seats  for  2,000  persons.  At  the  northwest  corner  of  the  building  is  a 
tower  i oo  feet  high  and  16  feet  square,  which  serves  as  a  fresh-air  shaft, 
down  which  the  air  is  drawn  by  a  fan  at  the  base  of  the  tower.  The 
entire  basement  of  the  church  is  a  fresh-air  chamber,  on  the  ceiling  of 
which  is  a  network  of  steam-heating  pipes,  2  inches  in  diameter, 
amounting  altogether  to  9,000  feet  in  length.  There  is  also  an 
auxiliary  coil  in  the  air  chamber  adjoining  the  fan,  containing  4,410  feet 
of  i-inch  pipe,  which  is  divided  into  four  separate  steam  coils,  each  of 
which  can  be  used  independently.  This  auxiliary  coil  is  in  itself 
nearly,  or  quite,  sufficient  to  furnish  ail  the  heat  required  under 
ordinary  circumstances.  But  the  pipes  beneath  the  floor  have  been 
found  very  useful  in  warming  the  floor  of  the  pews.  The  basement 
extends  under  the  entire  building,  and  is  about  9  feet  in  height.  It 
is  not  ceiled  or  plastered.  The  warm  air  forced  by  the  fan  into  this 
basement  air  chamber,  passes  into  the  body  of  the  church  through 
openings  in  the  risers  of  the  stationary  foot  benches  of  every  pew, 
these  openings  being  controlled  by  slats,  or  registers,  in  such  a  way 
that  the  occupant  of  each  pew  can  regulate  the  inflow  of  air  at  his 


CHURCHES. 


403 


FIG.  i53.-PLAN  OF  BASEMENT  OF  FIFTH  AVENUE  PRESBYTERIAN   CHUXCH, 

NEW  YORK  CITY. 


A. — Fresh-air  supply  shaft  from  tower. 
Entrance  for  air  75  feet  above  ground. 
B.— Fan. 

C.— Air  chamber. 
/?.— Heating  coil,  4,410  feet  of  i-inch  pipe. 


.E-Belt. 

F—  Engine. 

G.— Air  duct. 

L.—  Air  chamber  for  auditorium. 

M.— Coal. 


404  CHURCHES. 

pleasure.  The  air  also  escapes  into  the  aisles  through  openings  in 
the  ends  of  the  pews. 

Steam  is  usually  turned  into  the  pipes  underneath  the  floor  about 
24  hours  before  the  service  in  winter,  and  is  turned  off  when 
the  audience  begins  to  enter,  when  the  fan  is  put  in  motion.  The 
forcing  in  of  fresh  air  by  the  fan  is  continued  between  the  interval  of 
the  morning  and  afternoon  services,  thus  thoroughly  flushing  out  the 
church.  In  warm  weather  the  air  is  cooled  by  the  spray  of  water  from 
a  perforated  pipe  at  the  bottom  of  the  fresh-air  shaft,  and  by  the  use 
of  ice  the  temperature  of  the  incoming  air  has  been  lowered  as  much 
as  6  degrees. 

The  fan  is  similar  to  that  used  in  the  Capitol  at  Washington,  is 
7  feet  in  diameter  of  disk,  8.5  inches  wide  at  the  tips  of  the  blades, 
5  feet  in  diameter  at  the  mouth,  15  inches  width  of  blades  at  the 
mouth,  having  three-eighths  of  an  inch  clearance  between  the  edges  of 
the  blades  and  the  wall  or  fan  side,  with  an  area  of  19  square  feet  at 
the  mouth  and  15  square  feet  at  the  periphery.  The  area  of  the  duct 
or  passage  leading  from  the  chamber  is  20^  square  feet. 

The  results  of  some  experiments  made  upon  the  operation  of  this 
fan  by  Messrs.  Skeel  and  Nason  will  be  found  in  the  Journal  of  the 
Franklin  Institute  for  August,  1876,  page  97.  With  a  velocity  of  66 
revolutions  of  the  fan  per  minute,  the  velocity  of  the  air  in  the  delivery 
duct  was  found  to  be  484  feet  per  minute,  amounting  to  9,900  cubic 
feet  per  minute.  With  the  fan  running  at  no  revolutions  per  minute, 
the  number  of  cubic  feet  delivered  was  15,370.  The  authors  make  the 
following  comment.  Referring  to  experiment  No.  i,  when  9,900  cubic 
feet  of  air  was  supplied,  they  state  that  "  at  the  end  of  the  service  of 
one  and  a  half  hours,  with  1,400  people  in  the  church,  the  proportion 
of  carbonic  acid  in  the  air  was  found  to  be  12%  to  10,000." 

An  experiment  made  on  the  4th  of  June,  1876,  with  the  external  tem- 
perature at  84  degrees,  showed  that  with  the  delivery  of  631,000  cubic 
feet  of  air,  being  465  cubic  feet  of  air  per  man  per  hour,  the  speed  of  the 
air  through  the  registers  was  near  the  center  of  the  church  from  80  to 
135  feet  per  minute.  The  temperature  of  the  air  in  the  air  shaft  was 
77.  When  the  water  spray  was  turned  on  the  temperature  of  the  air 
entering  the  church  was  73,  the  temperature  of  water  itself  being  69. 

Complaints  have  been  made  at  times  by  some  of  the  audience  of 
unpleasant  draughts,  and  to  prevent  these  there  is  a  tendency  to  close 
the  registers  in  the  pews.  When  this  is  done  in  a  part  of  the  pews,  the 
effect  is  to  increase  the  velocity  of  the  current  through  the  remaining 
openings,  and  thus  to  induce  the  closure  of  these  by  the  persons  exposed 


CHURCHES. 


405 


FIG.  i-v— LONGITUDINAL  VIEW-FIFTH  AVENUE  PRESBYTERIAN   CHURCH. 


406  CHURCHES. 

to  such  currents.  It  is  therefore  impossible,  when  the  church  is  full,  to 
supply  the  amount  of  fresh  air  requisite  to  keep  the  proportion  of  car- 
bonic acid  down  to  8  parts  in  10,000,  which  is,  I  think,  a  fair  standard 
for  a  building  of  this  kind.  To  effect  this,  it  would  be  requisite  to 
increase  the  area  of  fresh-air  openings  in  the  floor,  and  probably  a 
good  way  of  doing  this,  without  producing  unpleasant  draughts  about 
the  feet  and  ankles  of  the  occupants,  would  be  to  have  the  partitions 
between  the  pews  made  hollow  and  used  as  air  ducts,  delivering  the 
fresh  air  directly  upward.  This  would  increase  the  amount  of  air  sup- 
ply, and  at  the  same  time  diminish  the  velocity  of  the  currents  through 
the  lower  openings  to  such  an  extent  as  to  remove  the  desire  to  close 
them  on  the  part  of  the  pew  holders. 

As  it  is,  however,  this  church  is  a  vast  improvement  on  the  great 
majority  of  such  structures,  in  which,  as  a  rule,  there  are  no  special 
arrangements  for  the  distribution  of  fresh  air  through  the  audience, 
and  the  effects  «f  the  steady  increase  of  impurity  in  the  air  are  usually 
distinctly  perceptible  in  the  audience  during  the  last  half  hour  of  the 
service. 

I  am  indebted  to  Mr.  S.  A.  Jellett,  of  the  Steam  Engineering 
Company,  Philadelphia,  Pa.,  for  the  following  description  of  the  new 
Hebrew  Temple,  North  Broad  Street,  Philadelphia: 

The  main  auditorium  of  the  new  Hebrew  Temple,  Keneseth- 
Israel,  a  plan  of  which  is  given  in  Fig.  154,  is  ventilated  by  means  of 
a  fan  located  at  the  point  E.  The  air  supply  is  obtained  through  the 
wall  openings  //.  The  fan  is  120  inches  high,  39  inches  wide  and  84 
inches  in  diameter,  with  an  inlet  of  42  inches  diameter  and  an  outlet 
of  38x38  inches.  At  the  outlet  begin  the  main  delivery  ducts  A  A, 
which  are  40  inches  in  diameter  at  this  point  and  gradually  decrease 
to  24  inches  diameter,  giving  off  at  regular  intervals  branches  for  sup- 
plying air  to  the  registers  at  the  floor  and  gallery  level  of  the  audito- 
rium. These  branches  are  given  off  at  an  angle  of  45  degrees  and  near 
the  wall  divide  into  two  smaller  branches,  one  of  which  directs  the  air 
over  a  steam  radiator  R  R  R,  and  thence  through  the  registers  on 
the  floor  of  the  room;  the  other  passes  directly  up  to  the  gallery  level 
without  being  heated,  the  idea  being  to  heat  the  air  only  at  its  low- 
est level.  The  aggregate  transverse  area  of  these  delivery  ducts  is 
29^4  square  feet  which,  with  a  velocity  of  687  feet  per  minute,  insures 
a  delivery  of  1,209,000  cubic  feet  of  fresh  air  per  hour. 

For  exhausting  the  air  from  the  auditorium  and  to  assist  in 
holding  the  warm  air  at  the  floor  of  the  building,  there  are  12  ventila- 
ting flues,  dotted  lines  B  B,  and  branches,  eight  of  them  coming  up 


CHURCHES. 


407 


FIG.  i54.-HEBREW  TEMPLE,  KENESETH-ISRAEL,    BROAD  STREET,  ABOVE 
COLUMBIA  AVENUE,  PHILADELPHIA,  PA. 

/  /.—Fresh-air  inlets.  .£.— Blower. 

f)\ Dampers  for  controlling  fresh  air  D. — Air  chamber. 

to  blower.  A  A,  etc.— Delivery  ducts. 

£.  — Dampers   for  controlling  air  from  R. — Radiators. 

auditorium  and  blower.  B. — Ducts  for  aspirating  air  from  audito- 
C.  -  Heating  coils.  rium. 


408  CHURCHES. 

in  the  end  of  the  pews  in  the  aisles,  and  the  other  four  coming  up 
against  the  front  of  the  pews  facing  the  main  platform.  These  12 
flues  are  each  4x15  inches  in  size,  and  drop  down  to  the  basement, 
v/here  they  connect  with  a  series  of  galvanized-iron  ducts  leading  to 
the  air  chamber  back  of  the  heating  coils  (b  on  plan).  They  have  a 
gradual  fall  from  the  farthest  connected  point  to  the  fans.  The  main 
duct,  where  it  enters  the  air  chamber,  is  controlled  by  a  sliding  damper 
which  works  on  the  wall  inside  the  air  chamber. 

The  point  aimed  at  in  this  arrangement  is  to  draw  the  upper  lay- 
ers of  warm  air  down  through  these  exhaust  ducts,  and  in  this  way 
warm  the  center  of  the  building  before  the  congregation  has  assem- 
bled; in  other  words,  to  counteract  the  aspirating  force  of  the  dome 
over  the  auditorium.  At  the  side  of  the  fan,  point  c  on  drawing,  is 
the  heating  chamber  for  the  air  that  is  to  be  propelled  by  the  fan 
through  the  delivery  ducts  A  A.  The  heater  consists  of  six  sections, 
containing  approximately  4,500  feet  of  i-inch  standard  wrought-iron 
pipe.  Four  of  these  sections  are  supplied  with  live  steam  at  low  press- 
ure, and  the  other  two  with  exhaust  steam  from  the  fan  engine. 
Each  section  is  controlled  by  separate  valves. 

The  air  capacity  of  the  auditorium  is  403,000  cubic  feet.  The 
glass  surface  is  estimated  at  2,126  square  feet,  the  exposed  roof  and 
dome  at  4,500  square  feet,  and  the  exposed  wall  at  5,580  square  feet. 
The  heating  surface  consists,  of  14  benches  of  indirect  radiators,  con- 
taining 1,360  square  feet  of  heating  surface,  and  a  fan  coil  containing 
3,600  feet  of  i-inch  pipe.  In  the  heating  coil,  used  as  a  fan  chamber, 
it  is  assumed  that  i  foot  of  i-inch  pipe  is  equal  to  i  square  foot  of 
heating  surface  based  on  ordinary  heating;  that  is  to  say,  i  foot  of 
pipe  will  condense  as  much  steam  with  the  fan  drawing  air  over  it  as 
3  feet  of  pipe  under  ordinary  conditions.  This  would  represent,  there- 
fore, a  total  heating  surface  of  4,960  square  feet  for  the  auditorium. 

The  Baptist  Church  of  Engiewood,  111.,  furnishes  a  good  illustra- 
tion of  the  method  of  heating  by  the  hot-blast  system  and  of  employ- 
ing an  exhaust  fan  as  an  auxiliary  in  producing  ventilation.  The  fresh 
air  is  delivered  mainly  through  floor  registers  around  the  periphery  of 
the  church  and  the  exhaust  is  also  taken  through  floor  registers  into 
a  large  room  in  the  basement  from  which  it  is  discharged  by  a  fan. 
The  plans  and  description  of  the  apparatus  are  given  in  The  Engineer- 
ing Record of  May  9,  1891,  and  it  is  stated  that  the  system  is  designed 
to  change  the  air  in  the  building  once  in  every  jo  minutes.  It  would 
be  interesting  to  know  what  its  effects  are  in  ordinary  use  as  shown 
by  air  analyses  and  by  measurements  of  the  velocities  in  the  ducts. 


CHURCHES.  409 

As  a  curiosity  in  the  way  of  radiating  surface  formulae  for  a 
church,  I  give  the  following  from  the  Civil  Engineering  and  Archi- 
tectural Journal,  1855,  Vol.  1 8,  page  107:  "To  the  number  of  cubic 
feet  in  the  church,  divided  by  300,  add  the  surface  of  walls  and  roof 
divided  by  120,  the  area  of  glass  divided  by  5,  the  superficial  surface  of 
doors  and  windows  divided  by  20,  and  the  number  of  cubic  feet  of  air 
withdrawn  in  ventilation  divided  by  6,  the  sum  is  the  number  of  square 
feet  of  hot  water  radiating  surface  required." 

To  secure  thoroughly  satisfactory  ventilation  of  a  church  at  all 
times  2,400  cubic  feet  of  air  per  head  per  hour  are  needed,  but  1,500 
cubic  feet  per  head  per  hour  will  give  good  results  under  ordinary  cir- 
cumstances. Probably  there  are  not  half  a  dozen  churches  in  the 
United  States  in  which  the  last-named  allowance  is  furnished  during 
cold  weather  for  the  full  seating  capacity  of  the  room,  although  it  may 
be  given  for  the  number  of  persons  actually  present. 


CHAPTER  XVIII. 

SCHOOLS. 

OF  all  classes  of  municipal  buildings  in  the  United  States,  public 
or  private,  there  are  probably  none  which  have,  until  recently, 
been  in  such  an  unsatisfactory  condition,  as  regards  their  ventilation, 
as  the  public  schools.  In  our  large  cities  they  still  are,  as  a  rule,  over- 
crowded and  insufficiently  supplied  with  air,  and  for  these  and  other 
reasons  which  I  need  not  here  specify,  they  are  probably  the  cause  of  a 
vast  amount  of  ill  health  and  premature  death,  although  these  results 
are  usually  not  so  direct  and  immediate  that  they  can  be  clearly 
traced.  Every  intelligent  teacher  knows  that  the  dullness  and  listless^ 
ness  in  some  pupils,  and  the  irritability  and  peevishness  in  others, 
which  are  so  manifest  toward  the  close  of  the  afternoon  session,  are 
closely  connected  with  the  gradual  accumulation  of  foul  air  which  has 
been  going  on  through  the  day.  If,  after  a  brisk  walk  in  the  open  air, 
you  enter  one  of  our  city  school  rooms  about  3  p.  M.,  you  will  in 
most  cases,  find  an  odor  which  is  far  from  being  agreeable,  and  which, 
under  such  circumstances,  is  the  characteristic  sign  of  insufficient 
ventilation. 

Taking  a  comparatively  recent  work  on  school  architecture,  which 
is  very  instructive  and  valuable  as  regards  the  general  plan  and 
arrangement  of  such  buildings,  we  find,  on  consulting  the  chapter  on 
Heating  and  Ventilation,  that  the  author  thinks  that  carbonic  acid  is 
the  specially  dangerous  impurity  that  is  to  be  gotten  rid  of,  and  that 
this  carbonic  acid,  when  cool,  falls  to  the  bottom  of  the  room,  but  as 
he  insists  that  all  foul-air  outlets  must  be  at  the  ceiling,  he  expects  to 
carry  off  the  greater  part  of  the  poison  before  it  has  time  to  settle. 
Steam  heating,  he  says,  cannot  pretend  to  be  of  use  for  schools. 

He  concludes  by  remarking  that  medical  men  seldom  speak  or 
write  upon  the  subject  without  displaying  much  scientific  knowledge, 
but  that  their  application  of  such  knowledge  is  not  so  successful. 
"  The  theory  of  extraction  from  the  bottom  instead  of  the  top  may  be 
scientifically  and  theoretically  the  best,  but  it  is  practically  inapplicable 


SCHOOLS.  411 

to  a  school  house.  *  *  *  Extraction  from  the  bottom  requires, 
from  its  great  friction,  so  enormous  a  motive  power  as  to  be  out  of  the 
question,  except  in  buildings  of  very  great  size." 

He  does  not  propose  any  particular  plan  for  ventilation,  but  says 
that  "  the  architect  should  exercise  his  own  judgment,  and  should 
invariably  intrust  the  carrying  out  of  the  work  to  some  engineer  specially 
accustomed  to  the  kind  of  appliances  and  arrangements  proposed  to  be  used" 
This  last  passage  is  a  solid  piece  of  wisdom,  and  as  such,  I  have 
ventured  to  italicise  it. 

Is  it  strange  that  the  school-house  architect  should  blunder  when 
such  is  his  instruction,  or  that  he  should  fall  an  easy  prey  to  the  first 
man  who  calls  himself  an  "  engineer,"  and  urges  on  him  the  merits 
of  his  patent  compound,  deflagrating,  ventilating,  lubricating  air  heater 
and  purifier? 

Within  a  few  years  there  has  been  a  change  for  the  better,  but  I 
am  compelled  to  believe  that  the  majority  of  architects  in  this  matter 
go  by  rule-of-thumb  instead  of  a  satisfactory  comprehension  of  the 
very  simple  principles  involved,  and  that,  moreover,  the  thumb  afore- 
said is  not  of  the  right  dimensions  or  proportions. 

A  good  illustration  of  this  appears  in  some  remarks  contained  in 
the  Builder  of  December  4,  1880,  p.  667.  The  writer  says  that"  he 
was  now  engaged  in  superintending  the  erection  of  two  schools,  one 
of  them  to  be  warmed  by  Mr.  Boyd's  hygiastic  grates,  and  the  other 
by  Leed's  American  steam-heating  system.  *  *  *  Unless  the  air 
was  heated  in  a  direct  manner,  just  as  the  atmosphere  was  warmed  by 
the  heat  imparted  to  the  earth  by  the  sun,  or  as  the  air  of  a  room  was 
warmed  by  the  heat  given  off  to  it  from  the  objects  warmed  by  the 
fire,  the  principle  proceeded  upon  was  wrong.  It  was  riecessary  to 
keep  to  direct  radiation;  in  other  words,  the  radiating  points  must  be 
in  the  room  to  be  heated,  and  not  in  chambers  or  places  remote  from 
it." 

From  this  it  would  seem  that  he  is  satisfied  that  steam  can  be 
used  in  heating  schools,  but  he  thinks  that  the  heating  derived  from  a 
coil  of  steam  pipe  in  a  room  is  of  the  same  character  and  presents  the 
same  advantages  as  that  from  the  rays  of  the  sun,  or  from  an  open 
fire — which  is  not  the  case.  Heating  by  a  steam  radiator  in  the  room 
to  be  heated  is  essentially  a  system  of  air  heating,  for  the  true  radiant 
heat  from  such  a  body  is  comparatively  small  in  amount  and  feeble  in 
effect. 

I  am  by  no  means  advising  that  every  architect  should  endeavor 
to  make  himself  an  expert  on  the  subject  of  heating  and  ventilation, 


412  SCHOOLS. 

but  he  ought  to  know  enough  of  these  subjects  to  be  aware  of  his  own 
ignorance,  and  to  be  able  to  judge  of  the  relative  merits  of  the  plans 
of  those  who  do  profess  to  be  experts,  and  who  come  to  him  seeking 
employment ;  and  also,  he  should  know  enough,  for  the  sake  of  his 
own  reputation,  not  to  be  dogmatic  in  his  assertions  about  the  merits 
of  this  or  that  method  which  he  has  never  seen  tried  and  with  regard 
to  which  he  has  no  scientific  data  whatever. 

In  planning  a  school  house  the  first  things  to  be  considered  are 
the  amounts  of  floor  and  cubic  space  and  of  air  supply  which  are  to 
be  allowed  each  scholar.  The  class  of  school  houses  which  we  are 
considering  are  those  of  such  size  and  importance  that  an  architect 
will  be  called  upon  to  prepare  plans  and  designs  for  them.  They  are 
usually  located  in  cities  where  space  is  limited,  and  the  amount 
allowed  for  their  construction  will  be  insufficient  to  secure  first-class 
work.  Under  these  circumstances  the  sanitarian  who  asks  for  a  lib- 
eral allowance  of  fresh  air  combined  with  a  comfortable  temperature 
and  freedom  from  draughts,  will  find  that  if  he  sets  a  high  standard 
his  views  will  be  promptly  condemned  as  being  impracticable.  When 
the  plans  are  in  course  of  preparation  the  average  board  of  school 
trustees  will  approve  of  any  number  of  flues  and  chimneys,  but  when 
it  comes  to  giving  out  the  heating  contract,  and  some  enterprising 
steam  fitter  offers  to  guarantee  perfect  heating  by  plading  coils  in  the 
school  rooms  under  the  windows,  for  about  one-half  the  cost  of  such 
an  apparatus  as  would  do  the  work  properly  and  furnish  fresh  air  at 
the  same  time,  the  said  board  will,  in  nine  cases  out  of  ten,  try  the 
cheap  plan,  with  the  usual  results. 

Let  us  see  what  some  recent  authorities  have  to  say  as  to  the 
proper  amount  of  air  space  and  air  supply  for  schools.  In  a  report 
made  to  the  International  Congress  of  Education,  held  in  Brussels  in 
1880,  Dr.  De  Chaumont  discussed  these  questions  fully,  and  his  paper 
should  be  consulted  as  representing  the  views  of  European  sanitarians 
on  this  subject. 

Taking,  as  a  starting  point,  the  experiments  of  Pettenkofer,  which 
show  that'  a  man  at  rest  exhales  266  cubic  centimeters  of  carbonic 
acid  per  hour  for  every  kilogram  of  his  weight,  and  making  the 
necessary  allowance  for  the  increase  due  to  movement,  speaking,  etc., 
he  concludes  that  a  child  in  the  school  room  exhales  about  346  c.c.  of 
carbonic  acid  per  hour  for  every  kilogram  of  its  own  weight.  The 
average  weights  of  children  of  different  ages  being  known  by  Quetelet's 
tables  and  De  Chaumont's  researches  (to  which  I  have  referred  in  a  pre- 
vious chapter)  having  shown  that  the  amount  of  carbonic  acid  derived 


SCHOOLS. 


413 


from  respiration  should  not  exceed  2  parts  in  10,000,  if  the  odor  of 
organic  matter  is  to  be  avoided,  he  has  from  these  data  computed  the 
following  table: 


Ages. 

Cubic  Meters  of 
Pure  Air  to  be  Sup- 
plied Per  Hour 

Cubic  Air  Space. 

No.  of  Pupils  for  a 
Room  Containing 
315  Cubic  Meters. 

A  years 

25   060 

8  650 

T.T. 

e                                                        .     . 

28  .  890 

9  630 

3O 

6                                     .    . 

•7  J      -32O 

IO   44O 

28 

7             
8                         

34.890 
38    5IO 

11.630 

12    840 

25 
2^ 

9              .  %  

41  .670 

13.890 

21 

10                              

45  200 

i  5  .  060 

10 

ii                .  .                

48  .  200 

16.070 

18 

12                     

53.630 

17.880 

16 

M 

6  1   100 

22    370 

14 

14 

70  060 

23    350 

12 

16 

92  .  200 

3O.73O 

9 

Adults           

118.  140 

39.380 

* 
7 

' 

It  will  be  seen  that  the  table  is  based  on  the  assumption  that  the 
air  in  a  school  room  cannot  conveniently  be  changed  oftener  than  once 
in  20  minutes,  and  that,  therefore,  the  cubic  space  in  such  a  room 
should  be  one-third  of  the  amount  of  air  to  be  supplied  per  hour. 
As  a  matter  of  fact,  this  amount  of  space  is  not  given  in  the  public 
schools  of  any  country,  because  of  the  great  expense  which  it  would 
involve,  nor  is  it  a  necessity,  since  the  above  calculations  are  based  on 
a  supposed  permanent  occupancy  of  the  room,  as  in  a  hospital  ward, 
whereas  the  school  room  is  occupied  but  a  few  hours  at  a  time,  and  can 
then  be  thoroughly  aired.  The  following  are  the  dimensions  fixed  by 
law  in  different  countries  or  recommended  by  those  who  have  given 
special  attention  to  this  subject,  the  data  being  derived  from  De 
Chaumont's  paper  above  referred  to  : 

Belgium.  —  By  law  i  square  meter  of  floor  space  and  4.5  meters  in 
height  to  each  scholar.  The  Educational  League  of  Belgium,  in  the 
plans  of  its  model  school,  proposes  1.67  square  meters  of  floor  space 
and  5.75  meters  in  height,  giving  9.6  cubic  meters  to  each  pupil. 

In  Holland  the  average  cubic  space  per  pupil  is  3.72  cubic 
meters  ;  in  89  schools  in  Haarlem  the  average  per  head  is  4.54  cubic 
meters.  In  England,  in  the  Board  Schools,  about  i  square  meter  of 
floor  space  and  from  3.65  to  4.25  meters  in  height  are  allowed  for  each 
scholar. 


414  SCHOOLS. 

Bavaria  prescribes  3.9  c.m.  for  scholars  of  eight  years  and  5.6  c.m. 
for  those  of  12  years.  The  public  schools  of  Dresden  give  an  average 
of  0.7  square  meter  of  floor  space,  and  4.38  c.m.  to  each  pupil. 

In  Frankfort  the  Medical  Society  advised  1.84  square  meters  of 
floor  space,  and  from  8.5  to  9.2  c.m.  per  head. 

At  Basel,  in  Switzerland,  1.45  square  meters,  and  from  4.21  to 
4.67  c.m.  per  head  are  prescribed.  In  Sweden  in  the  primary  schools 
1.52  square  meters  and  5. 35  to  7.55  cubic  meters* ;  in  the  higher  schools 
i. 58  to  2.17  square  meters,  and  7.69  to  9.98  cubic  meters  per  head  are 
given. 

In  New  York  City  from  2  to  3  cubic  meters  per  pupil  are 
allowed  theoretically,  but  the  actual  quantity  is  sometimes  much  less. 
Dr.  De  Chaumont  is  disposed  to  lay  some  stress  on  the  question  of  age 
and  to  take  the  ground  that  young  children  require  much  less  air  space 
and  air  supply  than  adults,  as  they  produce  so  much  less  carbonic  acid. 
He  would,  for  example,  put  three  times  as  many  children  of  four  or 
five  years  of  age  as  of  youths  of  15  or  16,  in  a  given  room.  This 
seems  to  me  to  be  very  doubtful.  The  question  of  amount  of  carbonic 
acid  exhaled  has  little  or  nothing  to  do  with  the  matter,  except  in  so 
far  as  it  is  an  index  of  the  amount  of  organic  matter  given  off,  and  it 
is  probable  that  the  difference  between  the  amount  of  organic  matter 
excreted  by  a  child  of  five  and  one  of  15  is  by  no  means  so  great  as 
would  be  indicated  by  the  carbonic  acid  test.  I  should  allow  in  a 
school  room  or  hospital  very  nearly  the  same  amount  of  air  supply  per 
head  for  children  of  all  ages  over  five  years  as  for  adults.  The  dimensions 
of  the  school  room  recommended  by  Dr.  De  Chaumont  are  10x7 
meters,  and  4^2  meters  in  height,  and  in  such  a  room  he  would  place 
from  i2  to  53  scholars,  according  to  their  ages. 

In  connection  with  the  paper  of  Professor  De  Chaumont,  above 
referred  to,  the  transactions  of  this  congress  contain  essays  by  M. 
Wazon,  a  French  engineer,  and  M.  Dekeyser,  a  Belgian  architect, 
upon  the  methods  of  heating  and  ventilating  schools.  M.  Wazon  takes 
20.5  cubic  meters  as  the  allowance  of  fresh  air  per  hour  per  head.  M. 
Dekeyser  allows  from  20  to  30  cubic  meters,  according  to  ages. 

Prof.  W.  Ripley  Nichols,  of  Boston,  in  a  report  on  the  sanitary 
condition  of  certain  school  houses  in  that  city,  dated  March  23,  1880, 
fixes  as  the  permissible  amount  of  carbonic  acid  in  school  rooms  i 
part  by  volume  in  1,000,  and  while  tacitly  admitting  that  this  is  a  low 
standard,  says  that  it  is  as  high  a  one  as  can  at  present  be  insisted  on. 
"  With  this  amount  of  carbonic  acid  there  will  undoubtedly  be  more  or 
less  of  the  '  school  odor/  especially  with  a  certain  class  of  the  scholars. 


SCHOOLS.  415 

To  obviate  this  entirely  would  require  an  amount  of  fresh  air  which 
could  not  be  practically  introduced  into  a  building  constructed  as  the 
Sherwin  School  is  ;  in  case  of  new  buildings  a  higher  standard  might  be 
obtained,  say,  0.8  or  0.9  volumes  of  carbonic  acid  in  1,000  volumes  of 
air ;  but  it  is  doubtful  whether  this  standard  could  be  reached 
without  a  larger  amount  of  floor  space  than  the  15  square  feet  usually 
allowed." 

The  amount  of  carbonic  acid  which  Professor  Nichols  actually 
found  in  the  school  rooms  of  the  Sherwin  School  varied  from  1.43  to 
2.29  parts  per  1,000. 

The  standards  which  I  would  fix  for  space  and  air  supply  in 
schools  are  those  given  in  the  report  of  the  special  committee  on  plans 
for  public  schools,  given  in  The  Sanitary  Engineer  for  March  i,  1880, 
and  reiterated  in  the  report  of  a  commission  on  the  public  schools  of 
the  District  of  Columbia,  dated  March  15,  1882,  and  printed  as  Mis. 
Doc.  No.  35,  House  of  Representatives,  Forty-seventh  Congress,  First 
Session — viz.: 

"  In  each  class  room  not  less  than  15  square  feet  of  floor  area  shall  be  allot- 
ted to  each  pupil. 

"  In  each  class  room  the  window  space  should  not  be  less  than  one-fourth 
of  the  floor  space,  and  the  distance  of  the  desk  most  remote  from  the  window 
should  not  be  more  than  i  ^  times  the  height  of  the  top  of  the  window  from 
the  floor. 

"  The  height  of  the  class  room  should  never  exceed  14  feet. 

' '  The  provisions  for  ventilation  should  be  such  as  to  provide  for  each  per- 
son in  a  class  room  not  less  than  30  cubic  feet  of  fresh  air  per  minute,  which 
amount  must  be  introduced  and  thoroughly  distributed  without  creating  un- 
pleasant draughts  or  causing  any  two  parts  of  the  room  to  differ  in  temperature 
more  than  2°  F.,  or  the  maximum  temperature  to  exceed  70°  F." 

It  must  be  remembered  that  the  above  represents  the  minimum  of 
requirement,  and  is  based  upon  the  requirements  in  cold  weather.  In 
warm  weather,  when  the  incoming  air  need  not  be  heated,  the  supply 
should  be  as  great  as  open  windows  and  doors  can  be  made  to 
furnish. 

The  usual  requirement  of  those  schools  in  this  country  for  which  the 
architect  will  be  called  in  to  prepare  plans,  will  be  that  they  shall  con- 
tain from  eight  to  12  class  rooms,  each  of  which  is  to  accommodate 
from  40  to  60  pupils,  and  that  these  are  to  be  arranged  in  connection 
with  a  large  central  hall  in  a  two-story  brick  building. 

In  some  cases  there  will  also  be  required  one  large  assembly  room, 
which  is  usually  placed  in  a  third  story.  The  heating  will  be  effected 
by  furnaces  or  steam,  the  tendency  being  to  increased  use  of  the  latter. 


4r6  SCHOOLS. 

The  trouble  with  furnaces  is  that  they  are  almost  invariably  set  in 
insufficient  number,  and  are  of  too  small  a  size. 

To  undertake  to  heat  such  a  schooHiouse  as  that  above  described 
with  one  or  two  furnaces  is  to  insure  bad  ventilation.  Not  less  than 
four  furnaces  are  necessary  in  such  a  building,  and  these  must  be  of 
the  largest  size,  giving  a  large  heating  surface,  costing  from  four  to  six 
hundred  dollars  each  when  properly  set. 

A  properly  arranged  and  well  constructed  steam-heating  apparatus 
for  such  a  building  will  cost  from  four  to  six  thousand  dollars,  depend- 
ing on  the  exposure,  etc.  Cheap  steam  heating  is  more  objectionable 
than  a  furnace.  As  a  rule,  school  rooms  are  overheated,  the  tempera- 
ture in  winter  in  our  schools  ranging  usually  from  72  degrees  to  76 
degrees.  The  rule  should  be  that  the  temperature  should  never  exceed 
70  degrees,  and  Dr.  Lincoln  is  no  doubt  correct  in  his  statement  that 
children  can  be  made  comfortable  at  66  degrees  in  a  well-aired  room. 

The  sensations  of  the  teacher  rather  than  those  of  the  scholars  usu- 
ally govern  the  regulation  of  the  temperature,  and,  as  Dr.  Lincoln  re- 
marks, "an  interesting  lesson  may  be  going  on,  or  a  written  examination; 
the  mind  works  well,  for  a  time,  at  a  fever  heat,  and  the  temperature 
of  84  degrees  may  pass  unnoticed.  It  is  needless  to  say  that  such  a 
strain  upon  the  system  is  followed  by  a  period  of  lassitude,  and  a  state 
of  lassitude  again  may  demand  a  slightly  raised  temperature.  Thus, 
by  degrees,  habits  of  preference  for  hot  rooms  may  be  found.  The 
teacher  may  be  as  unconscious  of  the  evil  as  the  scholar  ;  indeed,  if 
fatigued  she  may  require,  or  if  excited  may  not  notice,  an  unusual  heat. 
The  time  to  correct  bad  habits  in  this  respect  is  the  beginning  of  the 
school  year.  Every  one  then  comes  to  school  with  a  system  invigor- 
ated by  some  months  of  exposure  to  fresh  air,  and  if  care  is  taken,  this 
vigor  or  power  of  resisting  cold  may  be  retained."  To  this  I  would 
add  that  a  slight  modification  of  the  alarm  thermometer,  which  arouses 
the  keeper  of  a  greenhouse  by  the  ringing  of  a  bell  when  the  tempera- 
ture falls  below  a  certain  point,  can  be  easily  applied  to  secure  the  con- 
stant ringing  of  an  alarm  whenever  the  temperature  rises  above  70 
degrees,  and  that  such  an  instrument  would  be  a  very  useful  reminder 
and  not  very  costly. 

The  arrangements  for  ventilation  of  school  houses  by  architects 
relate,  as  a  rule,  mainly  to  the  removal  of  foul  air,  not  sufficient  attention 
being  given  to  amount  and  location  of  fresh-air  supply.  A  common 
method  of  construction  of  late  years  is  to  provide  an  eight  or  12- 
room  school  building  with  two  or  four  aspirating  shafts  or  chimneys 
connecting  with  the  various  rooms  and  having  an  aggregate  capacity 


SCHOOLS.  417 

sufficient,  with  a  velocity  in  these  shafts  of  about  8  feet  per  second, 
to  remove  from  15  to  30  cubic  feet  of  air  per  head  per  minute. 
The  air  supply  in  these  same  buildings  is  to  come  from  a  few  p-inch 
flues,  or,  as  in  the  Washington  school  buildings,  through  narrow  slits 
placed  beneath  the  window  sills.  The  plan  in  the  Washington  build- 
ings was  so  very  bad,  and  yet  was  so  highly  approved  by  some  persons, 
that  it  seems  worth  a  little  more  detailed  description.  The  fresh  air 
is  admitted  through  a  perforated  iron  plate,  set  in  the  walls  beneath  the 
sills  of  the  four  windows  in  each  room.  The  sum  of  the  area  of  clear 
opening  in  the  external  plate  of  each  window  is  from  22  to  25  square 
inches,  making  a  total  opening  for  the  supply  of  pure  air  for  the  room 
from  88  to  100  square  inches,  or  about  two-thirds  of  i  square  foot, 
which  would  not  give  5  cubic  feet  per  minute  per  pupil.  Having 
passed  through  the  perforated  plate  above  referred  to,  the  air  is  sup- 
posed to  pass  downward  through  a  narrow  slit  in  the  wall,  until  it 
reaches  the  level  of  the  floor,  when  it  turns  inward,  and  then  passes  up 
through  a  steam  radiator  set  against  the  window  breast.  Very  little 
air  comes  through  such  an  arrangement  in  comparison  with  what  is 
required,  but  even  this  little  is  carefully  shut  out  in  cold  weather  to 
prevent  draughts  and  the  freezing  of  the  pipes. 

This  method  of  heating  a  school  room  by  steam  pipes  placed  in 
the  room,  is  almost  sure  to  involve  a  defective  air  supply,  yet  it  is  one 
that  is  peculiarly  attractive  to  those  who  are  not  qualified  to  judge  of 
the  relative  merits  of  various  methods  of  heating,  since  it  is  compara- 
tively cheap  and  does  give  the  requisite  amount  of  warmth. 

The  practical  effect  of  such  a  system  when  connected  with  a  large 
aspirating  shaft  is  that  a  large  part  of  the  air  supply  in  the  class  rooms 
comes  from  the  central  hall,  as  will  be  seen  by  testing  the  direction  of 
the  currents  at  the  doors  and  transoms.  This  central  hall,  in  turn, 
derives  a  large  part  of  its  air  supply  from  the  basement  by  means  of  the 
stairways.  This  basement  air  is  liable  to  be  rendered  impure  by  the 
furnace,  and  by  the  water  closets,  if  they  are  placed  in  it,  which  should 
never  be  the  case. 

First  of  all,  then,  in  planning  a  school  house,  consider  the  air  sup- 
ply. With  regard  to  the  location  and  direction  of  the  openings  in  the 
school  rooms  for  the  admission  of  fresh  air,  they  should  either  be 
situated  above  the  heads  of  the  occupants  or  be  so  placed  as  to  give 
an  upward  current,  for  the  amount  of  floor  space  which  can  be 
afforded  to  each  pupil  is  so  small  that  some  of  them  must  be  placed 
in  unpleasant  proximity  to  registers  located  near  the  floor  in  the  ordi- 
nary way.  The  usual  location,  and  one  which  gives  good  results  if 


4l  BRIDGEPORT    SCHOOL. 

the  fresh-air  flues  and  registers  are  large  enough,  is  to  place  them  on 
the  outer  walls,  in  which  case  the  window  sills  are  a  convenient  place 
for  the  registers.  Mr.  W.  R.  Briggs  proposes  to  introduce  the  fresh 
air  on  the  inner  wall  at  a  point  about  two-thirds  of  the  distance  from 
the  floor  to  the  ceiling,  and  has  constructed  at  Bridgeport,  Conn.,  a 
high  school  upon  this 'principle. 

.  A  description  of  the  heating  and  ventilation  of  this  building  was 
published  in  the  Third  Annual  Report  of  the  Connecticut  State  Board  of 
Health,  and  a  part  of  this  appeared  in  The  Sanitary  Engineer  for  Decem- 
ber i,  1881,  from  which  I  take  the  following  description  and  illustrations: 

"  In  the  Bridgeport  school  the  coil  chambers  for  the  heating  of 
the  various  rooms  have  been  placed  in  the  main  ventilating  shafts  in 
the  center  of  the  building,  and  the  air  is  conveyed  from  them  through 
these  shafts  to  the  rooms  by  means  of  metal  flues.  The  air  enters  the 
inner  corner  of  the  room,  about  8  feet  from  the  floor.  The  outgoing 
flue  has  been  placed  directly  under  the  platform,  which  is  located  in 
the  same  corner  as  the  introduction  flue.  This  platform  measures  6x12 
feet,  and  is  supplied  with  castors,  so  that  it  can  be  moved  at  any  time 
it  is  necessary  to  clean  under  it.  Its  entire  lower  edge  is  kept  about 
4  inches  from  the  floor,  to  give  a  full  circulation  of  air  under  it  at  all 
points.  The  action  of  the  incoming  air  is  rapidly  upward  and  out- 
ward, stratifying  as  it  goes  toward  the  cooler  outer  walls,  thence  flow- 
ing down  their  surfaces  to  the  floor  and  back  across  the  floor  to  the 
outgoing  register  on  the  inner  corner  of  the  room.  By  this  method 
all  the  air  entering  is  made  to  circulate  throughout  the  room  before 
it  reaches  the  exhaust  shaft,  and  there  is  a  constant  movement  and 
mixing  of  the  air  in  all  parts  of  the  room  continually  going  on. 

"  The  inlets  are  all  intended  to  be  large,  and  the  flow  of  air 
through  them  moderate  and  steady.  The  atr  is  not  intended  to  be 
heated  to  a  very  high  temperature;  the  large  quantity  introduced  is 
expected  to  keep  the  thermometer  at  about  68  degrees  at  the  breathing 
level  The  school  rooms  contain  on  an  average  about  13,000  feet  of 
air,  or  260  cubic  feet  per  pupil.  It  is  proposed  to  supply  each  pupil 
with  30  cubic  feet  of  air  each  minute.  Allowing  50  pupils  to  each 
room,  this  will  necessitate  the  introduction  of  90,000  cubic  feet  of  air 
into  the  room  each  hour,  and  will  change  the  air  of  the  room  6.92 
times  within  the  hour,  or  once  in  about  eight  minutes.  These  calcu- 
lations are  based  on  a  difference  of  30  degrees  in  the  temperature. 

"  In  the  exhaust  flues  there  are  placed  coils  to  produce  a  strong 
up  current  at  all  times;  heat  is  also  obtained  from  radiation  from  the 
boiler  flues,  which  run  through  the  foul-air  shafts. 


BRIDGEPORT    SCHOOL. 


419 


"  The  heating  surface  for  each  room  is  inclosed  in  separate  cases  or 
jackets  of  metal,  and  is  then  subdivided  into  five  sections,  so  arranged 
that  any  number  of  sections  or  the  whole  may  be  used  at  pleasure- 
that  is  to  say,  that  any  one,  two  or  more,  up  to  five  parts,  may  be  used 
at  discretion.  In  extreme  cold  weather  the  whole  five  sections  are  in 
use;  in  moderate  weather  two  or  three,  and  when  a  small  amount  of 
heat  is  required,  only  one.  By  this  plan  the  supply  of  pure  air  re- 
mains always  the  same,  but  the  degree  to  which  it  is  heated  is  changed 
by  the  opening  or  closing  of  a  valve." 

This  arrangement  is  shown  on  the  accompanying  vertical  section 
of  a  coil  chamber,  which  represents  the  actual  construction  of  the  coil 
and  chamber,  A  B  C  D  £,  F,  on  the  section  of  building. 


FIG.  155.— VERTICAL  SECTION  OP  COIL  CHAMBER. 

These  large  dimensions  for  the  outlet  shaft  have  further  support 
in  the  mind  of  the  architect  in  the  necessities  for  summer  ventilation. 

The  results  obtained  from  this  arrangement  are  indicated  in  the 
report  of  an  examination  made  by  Dr.  Lincoln,  which  report  will  be 
found  in  The  Sanitary  Engineer  for  January  u,  1883. 

The  large  opening,  shown  in  the  plan  at  the  left  of  the  platform,  is 
into  the  assembly  room  through  folding  doors,  and  the  smaller  on  the 
right  into  the  hall.  The  circles  on  the  plan  indicate  the  position  of 
thermometers,  and  the  numbers  beside  them  are  those  used  in  the  fol- 
lowing table.  Where  two  numbers  are  attached  to  one  circle,  there  were 


420 


BRIDGEPORT    SCHOOL. 


two  thermometers,  one  above  the  other.     No.  i  was  at  the  center  of 
the  hot-air  register,  about  8  feet  above  the  floor ;  Nos.  2  and  3  at  a 


FIG.  156.— VERTICAL  SECTION  OF  SCHOOL  BUILDING. 

height  of  12  feet  above  the  floor   (about  as  high  as  the  instrument 
could  be  placed  in  a  vertical  position)  ;  Nos.  4,  5,  6,  7,  8,  9,  10  and  n 


BRIDGEPORT    SCHOOL. 


421 


at  a  height  of  5  feet  6  inches — level  of  bulb  ;  and  Nos.  12,  13,  14  and 
15  at  i  inch  above  the  floor,  No.  15  being  in  front  of  the  outlet. 


®8 


©10 


©13 


FIG.  157- 

The  thermometers  used  were  said  to  have  been  carefully  selected 
and  compared  with  each  other,  and  to  have  had  no  great  variation.  The 
room  had  been  closed  (before  the  afternoon  observation)  at  12.40.  A 
class  of  about  50  scholars — the  full  number — was  admitted  at  3 
o'clock,  and  dismissed  25  minutes  later. 


1 

Number  of  Thermo- 
meter on  Plan. 

DECEMBER  22,  P.  M. 

DECEMBER  23,  A.  M. 

2h.4cm. 

2h.  gom. 

^h.  iom.  3h.2sm. 

4h.  om. 

gh.  om. 

Qb.4om. 

loh.jm. 

j          

I08°F. 
74 
75 
69 
69 
69 

7i 
68 
70 
69 
70 
67 
66 

65 

68 

112° 
76 

78 
70 
71 
71 
73 
70 
72 
7t 
72 
67 
67 
65 
69 
37 

120° 
80 

84 

73 
74 
74 
76 
73 
/6 
75 
76 

70 
7i 

120° 

81+ 

85 
75 
76 

75 
78 
75 
77 
76 
77 
70 

119° 

84 
87 
76 
77 
77 
79 

90° 

104° 
70 
67 
63 
63 
62 

63 

135° 
80 

79 
68— 
69- 
69 

7.2 

o 

61 
61 
60 
60 

r 

6        

§ 

q            

78 
78 
79 

60 
60 
61 

62 
63 
63 

7i 
69 
70 

io         

II      .    .... 

12       

I  ^ 

60 

59 
61 

62 
60 
64 

69 
73 
36 

69+ 

57 

15      

Outside 

41 

Two  measurements  were  made  of  the  amount  of  air  coming  in. 
The  first,  at  about  2.50,  showed  nearly  800  cubic  feet  per  minute,  and 


422  JACKSON    SCHOOL. 

the  second,  at  3.15,  nearly  1,000  cubic  feet  per  minute,  or  20  cubic 
feet  per  pupil. 

In  the  words  of  Dr.  Lincoln,  "  abundant  proof  was  given  that  the 
current  passes  very  rapidly  across  the  ceiling,  quickly  down  the  ex- 
posed (outer)  walls,  then  slowly  back  across  the  room  to  the  outlet ; 
the  range  of  temperature,  regularly  falling  in  about  this  order,  fur- 
nishes a  proof  of  this,  and  further  evidence  was  fully  given  by  the 
action  of  the  anemometers  at  the  ceiling  and  at  the  outer  exposed 
faces  of  the  room. 

"  In  the  latter  situation,  the  current  was  invariably  downward,  and 
the  elevated  temperature  at  the  windows  will  be  noticed. 

"  To  answer  a  question  as  to  the  temperature  at  the  level  of  the 
pupils'  bodies,  a  thermometer  was  placed  upon  a  desk  at  14.  In  the 
last  two  trials  (right-hand  columns)  the  readings  of  Nos.  3,  9,  the 
new  thermometer,  and  14  (respectively  placed  at  the  ceiling,  at  5j/> 
feet  from  floor,  at  the  desk  level,  and  at  the  floor),  were  67,  62,  60,  59 
degrees;  and  79,  71,  63  and  60  degrees." 

The  motive  power  for  ventilation  of  ordinary  medium-sized  school 
buildings  may  be  furnished  by  fans,  or  by  an  aspirating  shaft  or  chim- 
ney, but  as  a  rule  two  of  the  latter,  one  on  either  side  of  the  central 
hall,  are  to  be  preferred  if  aspiration  only  is  to  be  employed.  The 
size  of  these  shafts  will  be  determined  by  the  fact  that  the  velocity 
in  them  should  be  from  6  to  8  feet  per  second.  Knowing  the  total 
amount  of  air  to  be  moved  per  second,  the  calculation  is  very  simple. 
If  it  be  decided  to  use  but  one  large  aspirating  shaft  for  the  whole 
building,  the  best  results  will  be  obtained  by  carrying  all  the  foul-air 
flues  downward,  and  having  them  open  at  the  bottom  of  the  shaft. 

Of  late  years  the  use  of  fans  in  school-house  ventilation  is  becom- 
ing common,  and  excellent  results  may  trjus  be  obtained.  The  hot- 
blast  system  is  better  adapted  for  use  in  schools  and  office  buildings 
than  it  is  for  buildings  which  are  permanently  occupied,  and  two  ex- 
amples of  its  use  are  here  given. 

The  new  Jackson  School  building  in  Minneapolis  is  of  brick, 
90x130  feet,  three  stones  high,  intended  to  accommodate  1,056 
pupils,  and  is  warmed  and  ventilated  by  a  hot-blast  system  which 
delivers  the  fresh  air  into  the  rooms  through  openings  2  feet  square 
placed  about  6  feet  above  the  floor.  It  was  required  that  the  heating 
plant  should  raise  the  temperature  from  minus  40°  to  plus  70°  F., 
and  maintain  the  same  as  long  as  required  ;  and  that  the 
ventilation  plant  should  furnish  3,000,000  cubic  feet  of  fresh  air  per 
hour,  warmed  to  70°  F. 


JACKSON    SCHOOL. 


423 


Figure  158  is  a  plan  of  the  ground  floor  containing  the  boys' 
manual  training  rooms,  B  C  K;  water  closets  A  D  ;  class  rooms 
E  F I  J\  fuel  room  H,  and  boiler  room  Z.  The  steam  pipes  are 


FIG.  158. 

run  overhead,  and  are  here  indicated  by  heavy  full  lines  for  the  direct 
mains,  and  by  heavy  broken  lines  for  the  dry  returns  to  boiler  room. 


424 


JACKSON    SCHOOL. 


Figure  159  is  a  plan  of  the  main  floor.  A  is  a  calisthenics  hall,  and 
there  are  eight  class  rooms  and  two  recitation  rooms.     The  second 


FIG.  i5Q. 

floor  is  similar  to  the  first.      Jt  Jt,  etc.,  are  direct  steam  radiators, 
chiefly  of  the  Haxtun  make,  of  wrought-iron  pipe,  standard  height.    S 


JACKSON    SCHOOL. 


425 


S  are  Detroit  radiators,  60  inches  long  and  of  standard  height.  T  T 
are  Joy  draft  tube  radiators,  37  inches  long.  B  B,  etc.,  are  heating 
and  ventilating  shafts  that  contain  separate  cylindrical,  galvanized-iron 
flues  for  each  room.  Their  openings,  C  C  D  D,  etc.,  measure  for 
the  class  rooms  2x2  feet,  and  for  the  recitation  rooms  2/xiV'-  E  is  the 
belt  shaft  for  the  exhaust  fan. 


FIG.  160. 


O 


O 


(ZD 


FIG.  161 


Figure  161  is  a  plan  of  the  boiler  room  Z,  Fig.  158.  Figure  160 
is  an  elevation  at  N  N,  Fig.  161.  A  A  are  48"xi4'  steel,  tubular 
boilers.  B  is  an  Atlas,  self-contained,  15  horse-power  engine,  with 
pulley  F  vertically  under  the  attic  exhaust  f?n,  which  it  drives  by  a 
belt. 


426 


JACKSON    SCHOOL. 


The  pulley  H  drives  the  fresh-air  tan  in  an  adjacent  room.  Both 
fans  are  Kelley  Excelsiors,  72  inches  diameter,  made  by  the  Preble 
Machine  Company,  Chicago. 

The  pressure  fan  delivers  fresh  air  to  the  indirect  radiator  stack, 
made  by  the  Haxtun  Steam  Heating  Company,  of  Kewanee,  111.  This 
stack  contains  4,752  feet  of  i-inch  pipe,  made  into  six  radiators,  60 
inches  long,  with  standard  bases  and  supply  and  return  connections  at 
opposite  ends,  and  without  tops  or  legs.  G  is  a  Worthington  duplex 
boiler  feed  pump.  D  is  a  3o"x8'  return  tank  with  manhole  and  hand- 
hole. 


PIG.  162. 


Figure  162  shows  the  method  of  setting  Joy  draft  tube  radiator 
y,  here  used,  so  as  to  obtain  direct  radiation  when  ventilation  is  not 
required,  leaving  the  ventilation  under  the  control  of  the  occupant  of 
each  room.  Fresh  air  is  admitted  through  an  opening  O  beneath  win- 
dow W^  and  delivered  through  a  galvanized-iron  duct  Z>to  the  register 
R.  This  controls  its  admission  to  the  room. 

Further  details  in  regard  to  the  heating  apparatus  of  this  school 
are  given  in  The  Engineering  Record  si  June  9  and  June  20,  1891. 

The  cost  of  the  steam  heating,  ventilating  and  flue  work  is  given 
as  $7,214,  and  it  requires  about  one  ton  of  Illinois  coal  per  day. 


JACKSON    SCHOOL. 


427 


FIG.  163. 


428  GARFIELD    SCHOOL. 

Figure  163  is  a  plan  of  the  basement  of  the  Garfield  School  in 
Chicago,  which  school  consists  of  two  buildings,  each  of  three  stories 
and  basement,  and  containing  12  class  rooms. 

The  reference  letters  indicate  as  follows:  A  A,  etc.,  ceiling  coil 
radiators  of  i^-inch  pipe,  £  a  36-inch  exhaust  fan,  1?  F,  etc.,  are 
galvanized-iron  foul-air  ducts,  from  closet  rooms  only,  of  rectangular 
cross-section,  generally  18x20  inches,  or  of  equivalent  sectional  area, 
and  carried  on  the  ceilings.  These  are  concentrated  in  a  chamber  in 
front  of  a  36-inch  exhaust  fan.  F  is  an  8xi 2-inch  Atlas  engine  of  15 
horse-power  (indicated),  which  drives  shaft  Cand  the  72-inch  Sturte- 
vant  blower  G  through  belts  H  H.  D  D  are  fresh-air  ducts  to  class 
and  recitation  rooms,  similar  to  F  F,  etc.  /  is  a  return  tank  and  J  is 
a  5K'X3^'X5"  Worthington  duplex  pump  for  boiler  feed  water  and 
house  supply.  K  is  a  pressure-regulating  valve,  and  L  is  a  grease 
trap.  At  J/are  three  primary  radiators,  each  4'x32'x6"  high,  having  a 
combined  total  surface  of  768  square  feet,  and  placed  on  a  platform  36 
inches  high.  At  JV^  are  nine  secondary  radiators,  each  4'x32'x6"  high, 
and  having  a  combined  surface  of  2,304  square  feet.  O  O  are  first- 
floor  registers. 

P  is  an  8xi2-inch  Atlas  engine  of  15  horse-power  (indicated), 
driving  through  belt  H  the  72-inch  Sturtevant  blower  Q.  At  Jt  are 
three  primary  radiators,  each  4'x32'x6*  high,  with  a  combined  surface 
of  768  square  feet,  and  placed  on  a  platform  2x6  inches  above  the 
floor.  At  S  are  nine  secondary  radiators,  each  4'x32'x6"  high,  and 
having  a  combined  surface  of  2,304  square  feet.  T  T  are  two  54X  14- 
inch  steel  boilers,  made  by  the  John  Davis  Company,  each  containing  39 
4-inch  tubes.  U  is  the  smoke-stack;  V  is  the  indirect  and  W  the 
direct  steam  main;  X  is  the  pressure  regulator,  Kand  K1  are  the  old 
brick  ventilation  shafts  that  now  contain  separate  galvanized-iron 
flues  from  different  rooms,  and  are  extended  up  through  to  the  top  of 
the  roof.  ZZare  risers,  to  supply  steam  to  the  direct  radiators  in  the 
upper  stories,  each  horizontal  branch  being  connected  to  one  wall  coil 
with  generally  104  square  feet  of  surface  of  i^-inch  pipe. 

The  indirect  supply  mains  are  shown  throughout  by  full  black 
lines,  and  the  direct  supply  mains  by  lines  broken  with  one  dot. 

a  and  a'  are  the  boys'  and  b  and  b'  are  the  girls'  water  closets,  c  c 
is  a  hall  which  is  used  for  a  passageway,  Z  is  the  exhaust  chamber 
for  foul-air  flues  from  the  closets  in  which  the  36-inch  fan  is 
placed,  d  is  a  boys'  play  room,  c  and  c'  are  teachers'  toilet  rooms, 
/  is  the  engine  room,  g  is  the  cold  chamber  to  which  fresh  air 
(as  indicated  by  the  arrows)  is  admitted  through  adjacent  external 


GARFIELD    SCHOOL. 


429 


windows,  and  passing  through  radiators  M  and  the  blower  C  is 
forced  through  radiators  N  in  the  hot  chamber  h  and  into  the 
distributing  chamber  /,  which  has  been  adapted  from  an  old  brick 
chamber  for  a  furnace,  up  whose  original  flues,  together  with  those  of 
the  other  furnace  at  u  (which  are  connected  by  galvanized-iron  ducts) 
the  hot  air  is  delivered  to  the  upper  stories.  Continuing,  i  is  a  play 
room,/,  boiler  rooms,  and  k  is  a  coal  room.  The  old  brick  foul-air 


FIG.  164. 

flues  formerly  used  in  connection  with  furnace  ventilation  are  now 
used.  A  separate  flue  /,  extends  from  each  class  room  to  the  top  of 
the  roof.  In  this  figure,  ///  is  the  girls'  play  room;  n  «,  a  hall;  o, 
engine  room;  q,  the  cold-air  chamber  in  which  the  fresh  air  is  re- 
ceived, as  indicated  by  arrows,  from  adjacent  external  windows,  and 
drawn  through  radiators  .R  by  blower  (?,  which  forces  it  through  radi- 
ators S  in  the  hot  chamber/  and  thence  through  galvanized-iron  ducts 


43° 


GARFIELD    SCHOOL. 


to  the  flues  of  the  original  hot-air  furnaces  at  /  and  w;  /  is  a  vertical 
shaft  into  which  the  exhaust  pipe  from  engine  P  is  taken  up  to  the  top 
of  the  same;  s  is  a  play  room,  x  x  are  i^-inch  horizontal  direct  steam 
pipes  to  risers  for  wall  coils,  and  y  y  are  upright  branches  to  radiators 
on  the  first-story  hall. 


FIG.  165. 

Figure  164  is  a  plan  of  the  basement  of  the  old  part  of  the  Gar- 
field  School,  showing  the  original  arrangement  of  heating  by  the  fur- 
naces A  A.  B  B  were  ventilating  shafts  ;  G,  the  coal  room  ;  H,  hall  ; 
/,  girls',  and  y,  boys'  play  room  ;  K,  boys'  and  Z,  girls'  water  closets; 
and  M  M,  teachers'  toilet  rooms. 


GARFIELD    SCHOOL. 


431 


Figure  165  is  a  plan  of  the  first  story  of  the  old  part  of  the  Gar- 
field  School,  showing  the  original  arrangement.  Warm  air  from  the 
furnaces  was  admitted  from  the  flues  marked  i,  i,  etc.,  while  those 
marked  2  and  3  delivered  it  to  the  second  and  third  stories,  respec- 
tively. Foul  air  was  withdrawn,  as  indicated  by  arrows,  upward 
through  the  ducts  D  D,  etc.,  of  ventilation  shafts  B  B,  the  ducts 


FIG.  1 66. 

D2  D.^  serving  for  second  and  third  stories,  respectively,  E  E,  etc., 
serving  the  basement  closets,  and  F  F,  etc.,  being  the  radiator  ducts 
which  accelerated  by  conduction  the  circulation  in  the  adjacent  ducts. 
Rectangular  tin  foul-air  flues  between  basement  ceiling  and  first  floor 
connected  remote  class  rooms  with  flues  D  Z>,  and  are  here  shown  by 
dotted  lines.  P  P,  etc.,  were  class  rooms;  W  W,  wardrobes;  S,  hall, 


432 


GARFIELD    SCHOOL. 


and  R  R  registers  27x38  inches.     H  H  are  auxiliary    wall  flues  for 
ventilation. 

Figure  1 66  is  a  plan  of  the  first  floor  of  the  old  part  of  the  Gar- 
field  School,  showing  present  arrangement.  Y  Y  U  T  and  6°,  are  the 
same  vertical  lines  of  ducts  and  flues  that  are  indicated  by  the  same 
letters  in  Fig.  163,  those  at  6°,  U  and  T,  delivering  fresh  air  and  com- 
prising three  separate  ducts  each,  which  terminate  at  the  first,  second, 
and  third  stories,  respectively,  as  indicated  by  the  corresponding  numer- 
als which  show  which  floor  they  serve.  At  £7  and  T  the  original  single 
duct  has  been  divided  by  galvanized-iron  partitions,  as  shown,  to  make 
separate  passages  for  each  room,  and  an  additional  galvanized-iron 


FIG.  167. 

iiue  N,  has  been  added  alongside  for  the  third-story  rooms.  Ducts  6° 
have  been  especially  built  of  galvanized  iron.  Similarly  six  galvanized- 
iron  flues  have  been  placed  in  old  shafts  Y  and  y,  to  afford  separate 
service  to  the  different  rooms,  two  in  each  shaft,  terminating  at  each 
of  the  three  upper  floors.  All  of  these  opening  are  provided  with  reg- 
isters, those  for  warming  being  near  the  ceilings  and  those  for  ventila- 
tion being  near  the  floor.  O  is  a  hot-air  register,  and  A  A,  etc.,  are 
old  registers  now  closed.  B  B,  etc.,  are  supplementary  direct  radiator 
coils,  each  of  about  100  square  feet  and  connected  as  shown  to  supply 
and  return  steam  risers  S  and  R. 


BRYN    MAWR    SCHOOL. 


433 


For  further  details  see  The  Engineering  Record  for  December  19, 
1891,  and  January  2,  1892. 

As  an  example  of  a  boarding  school  heated  and  ventilated  by  a 
hot-blast  system,  I  give  the  plans  of  part  of  the  Bryn  Mawr  school 
near  Philadelphia,  for  which  I  am  indebted  to  Mr.  Jellett,  the  engi- 
neer of  the  Steam  Engineering  Company,  of  Philadelphia. 

Figure  167  is  a  plan  of  that  part  of  the  basement  containing  the 
heating  apparatus.  A  is  the  blowing  fan,  having  an  outlet  38  inches 
square.  B  is  the  heating  coil,  with  1,400  square  feet  of  heating  sur- 
face. The  main  air  duct  from  this  coil  is  45  inches  in  diameter  and 
divides  into  two  ducts,  one  32  inches  and  the  other  31  inches  in 


FIG  168. 

diameter.  The  32-inch  branch  is  210  feet  long  and  supplies  59  verti- 
cal flues  varying  in  size  from  4x12  inches  to  6x14  inches.  The  3i-inch 
branch  extends  112  feet  and  supplies  24  vertical  flues  varying  in  size 
from  5x12  inches  to  6x15  inches. 

Figure  168  shows  arrangement  of  first  and  second  floors,  the 
points  of  delivery  and  exit  of  air  being  indicated  by  arrows. 

Figure  169  is  a  plan  of  part  of  the  third  floor  and  loft,  showing 
foul-air  ducts  C  C,  uniting  to  deliver  into  a  large  vertical  tower  shaft. 

All  rooms  not  supplied  with  fireplaces  and  chimney  flues  have  up- 
cast foul-air  flues.  In  the  tower  shaft  is  an  accelerating  steam  coil 
heated  by  steam  at  ,50  pounds  pressure. 


434 


COLLEGE    OF    PHYSICIANS    AND    SURGEONS. 


The  steam  heating  and  ventilating  apparatus  in  the  building  of 
the  College  of  Physicians  and  Surgeons,  of  New  York  City,  was  ar- 
ranged by  Mr.  William  J.  Baldwin,  and  presents  some  features  of 
special  interest.  Both  hot  and  cold-air  ducts  are  carried  to  each 
room,  except  the  amphitheaters  and  dissecting  room,  so  that  the  tem- 
perature of  the  room  can  be  controlled  by  the  occupant.  Four  fans, 
each  6  feet  in  diameter,  are  used,  two  of  them  furnishing  air  slightly 
warmed,  or  with  the  chill  off,  and  two  air-heated  to  the  usual  degree. 
The  mode  in  which  the  twin  ducts  are  arranged  is  shown  in  Fig.  46, 
page  270. 


FIG.  169. 


Figure  170  shows  the  general  cellar  plan  and  a  vertical,  longitudi- 
nal section  through  the  middle  building  of  the  group  of  three,  and 
shows  the  main  features  of  the  whole  system. 

The  fans,  four  in  number,  are  each  6  feet  in  diameter,  and  from 
1,000,000  to  1,250,000  cubic  feet  capacity  each,  according  to  the  speed 
at  which  they  are  run.  All  the  engines  and  pumps  exhaust  into  a  5- 
inch  main  exhaust  pipe  which  extends  to  the  roof  of  the  building.  A 
branch  from  this  pipe  leads  to  a  feed  water  heater  and  back  again  into 
the  pipe.  Another  branch,  5  inches  in  diameter,  supplies  exhaust 
steam  to  the  coils  in  the  casings  A  A  B  CD  G  and  Z,  after  the 
steam  has  been  passed  through  a  "  skimming  tank,"  where  the  oil  from 
the  engines  is  separated  from  it.  These  coils  are  of  the  gridiron 


COLLEGE    OF    PHYSICIANS    AND    SURGEONS. 


435 


type,  made  up  of  a  number  of  sections  each.  The  sections  have  an 
average  length  of  10  feet,  not  including  the  spring  pieces,  which  meas- 
ure about  2  feet.  The  pipes  of  the  coils  are  covered  with  secondary 


FIG.  170. 


wire  surface,  made  of  No.  14  square  iron  wire,  and  known  as  Gold's 
compound  coil  surface.  The  coil  stands  are  made  of  pipes  and  fittings 
and  are  so  arranged  that  each  section  can  be  drawn  out  for  repairs 


436  COLLEGE    OF    PHYSICIANS    AND    SURGEONS. 

without  disturbing  those  others.  Each  section,  moreover,  is  fed  separ- 
ately by  a  2-inch  steam  pipe  with  a  valve  in  the  engine  room,  and  the 
return  pipes  also  come  separately  into  the  engine  room.  The  coils  are 
inclosed  in  galvanized-iron  casings,  open  at  the  bottom,  and  connect- 
ing with  the  air  ducts  at  the  top,  as  shown  more  clearly  in  the  vertical 
section.  Swinging  dampers  are  arranged  in  the  bottoms  and  near  the 
tops  of  these  casings,  so  that  a  mixture  of  hot  and  relatively  cold  air 
may  enter  the  distributing  ducts,  the  proportions  being  readily  con- 
trolled by  opening  or  closing  the  different  dampers. 

In  front  of  the  four  fresh-air  inlet  windows  primary  steam  coils  S, 
supplied  with  live  steam,  are  set  up.  These  coils  aggregate  about 
i, 600  lineal  feet  of  i-inch  pipe,  covered  with  secondary  wire  surface, 
as  in  the  case  of  the  main  heating  coils.  The  entering  air,  which  thus 
receives  what  may  be  called  an  initial  heating,  reaches  the  settling 
chambers,  marked  on  the  plan,  and  from  these  is  drawn  by  the  fans 
into  the  four  heating  chambers,  containing  the  coils  and  casings  A  A\ 
B  C  D  L  and  G.  The  coils  B  and  G  are  not  ordinarily  supplied 
with  steam,  but  are  designed  to  be  used  as  substitutes  for  the  coils  A 
and  D  in  case  of  repairs,  in  which  case  the  "warm  "  duct  would  be 
used  as  the  "  hot  "  one.  It  should  be  remembered,  also,  that  the  air 
ducts  from  A  and  B  and  from  D  and  G  together  lead  to  twin  flues 
and  discharge  into  the  same  rooms.  The  air  which  passes  into  the 
casings  B  and  G,  therefore,  is  not  further  heated,  but  is  simply  at  that 
comparatively  low  temperature  which  has  been  imparted  to  it  in  pass- 
ing through  the  primary  coils.  The  air  which  passes  through  the 
casings  A  and  JD,  on  the  other  hand,  is  further  heated  to  the  much 
higher  temperature  due  to  the  hot  coils  within.  The  hot  and  warm- 
air  supplies  from  the  casings  A  and  B  and  D  and  G,  discharge  into 
the  same  register  boxes,  as  already  intimated,  and  the  proportions  of 
each  maybe  varied  by  special  slide  valves  at  the  register  face.  These 
valves  or  dampers  are  so  constructed  that  they  will  allow  the  air  from 
one  of  the  twin  flues  to  escape  separately,  or  admit  a  part  of  the  air 
from  each  flue,  one  flue  opening  in  the  proportion  the  other  is  closed. 
Two  streams  of  air  of  different  temperatures  may  thus  be  admitted  to 
the  register  box,  where  they  mix  and  then  pass  through  the  register 
face,  and,  at  the  same  time,  it  is  beyond  the  power  of  the  occupants  of 
the  rooms  to  shut  off  both  pipes  at  the  same  time.  The  ducts  leading 
in  the  dissecting  room,  amphitheater  and  lecture  room,  from  the  casings 
C  A'  and  Z,  supply  only  warm  air,  the  temperature  of  which  is  regu- 
lated by  the  engineer,  the  double-duct  system  not  being  used  for  these. 
The  lecture-room  duct,  as  shown  in  the  vertical  section,  discharges 


COLLEGE    OF    PHYSICIANS   AND    SURGEONS. 

P 


437 


FIG.  171. 


PIG. 


438 


COLLEGE    OF    PHYSICIANS    AND    SURGEONS. 


into  the  space  under  the  seats,  and  from  there  the  warm  air  issues  into 
the  room  through  openings  in  front  of  each  row  of  seats.  The  warm- 
air  discharge  into  the  amphitheater  is  effected  in  the  same  way. 

Figure  172  is  a  plan  of  the  dissecting  room  on  the  fourth  story. 
The  hot-air  flues  pass  up  to  the  galvanized-iron  perforated  cornice, 


FIG.  173. 


MASSACHUSETTS    VENTILATION    LAW. 


439 


shown  in  Fig.  171.  Opposite  each  flue  opening  is  a  deflector  Z>, 
Fig.  171,  to  turn  the  air  along  the  line  of  the  cornice,  and  thus 
secure  diffusion  of  the  incoming  currents. 

Figure   173   is  a  plan   of  the  space  between  the  ceiling  of  the 
dissecting  room  and  the   roof.      The   hot   air  from   the  ventilating 
cornice  becomes  chilled  by  the  glass  of  the  sky- 
lights  and   descends    to   the   floor,   where   the 
openings  of  the  foul-air  ducts  are  placed. 

Figure  174  is  a  vertical  section  of  the 
rooms  in  which  the  foul-air  ducts  V  are  shown. 
These  ducts  join  and  lead  to  the  aspirating 
shaft  A,  as  shown  in  Fig.  173. 

Figure  175  is  a  perspective  view  of  the 
direct-indirect  hot-water  radiators  in  a  fourth- 
floor  class  room  of  the  Berkeley  School  in  New 
York,  and  Fig.  176  is  a  section  of  one  of  these 
radiators.  The  fresh  air  enters  the  flue  A, 
through  the  grating  B,  the  quantity  admitted 
being  controlled  by  the  damper  D.  Figures 
177  and  178  show  similar  arrangements  in  other 
class  rooms. 

In  this  building  the  motion  of  the  air  is 
produced  by  an  aspirating  fan  in  the  attic  draw- 
ing from  wall  flues  opening  into  each  room.* 

In  concluding  this  part  of  the  subject, 
attention  is  called  to  the  fact  that  whatever  be 
the  system  of  ventilation  adopted,  it  should  be 
supplemented  by  daily,  systematic  and  thorough 
aeration  of  the  building  morning  and  evening. 
No  doubt  this  will  chill  the  rooms  in  cold 
weather,  and  will  increase  the  expenditure 
for  fuel,  but  this  is  a  necessary  and  legitimate 
expense. 

In  1888  the  State  of  Massachusetts  en- 
acted that  "every  public  building  and  every 
school  house  shall  be  ventilated  in  such  a 
proper  manner  that  the  air  shall  not  become 
so  exhausted  as  to  become  injurious  to  the 
health  of  the  persons  present  therein/',  and 
directed  that  this  should  be  enforced  by  the 


FIG.  174. 


*  See  The  Engineering  Record,  April  9,  1892. 


440 


MASSACHUSETTS    VENTILATION    LAW. 


inspection  department  of  the  district  police  force.  The  annual  reports 
of  the  chief  of  the  Massachusetts  district  police  published  since 
that  date  contain  some  interesting  information  with  regard  to  the 


FIG.  175. 


ventilation  of  the  school  houses  of  the'  State,  with  numerous  plans 
and  pictures  of  school  houses,  some  apparently  furnished  by  the 
proprietors  of  patent  systems  as  a  sort  of  advertisement. 


Wnc/oitr 


FIG.  r76. 


"  The  State  requires  that  30  cubic  feet  of  properly  warmed  fresh 
air  be  supplied  for  each  pupil,  and  an  equal  amount  of  foul  air  removed 


MASSACHUSETTS    VENTILATION    LAW. 


44 1 


from  the  school  room  per  minute,  without  subjecting  the  pupils  to 
objectionable  draughts  ;  that  the  temperature  be  maintained  at  70 
degrees  during  the  coldest  weather,  and  not  vary  more  than  2  degrees 
at  any  point  in  the  room  at  the  level  of  the  breathing  line  of  the 
pupils.  The  carbonic  acid  test  should  not  give  more  than  8  parts  in 
10,000  of  air."  * 


Window 


00 

oo 

ooobooo 
,  oo 
v ooopooo 
0  000,0000 

ooooooo 

ooooooo 

OOOJDOOO 


FIG. 


FIG.  178. 


The  general  effect  of  the  law  has  been  good,  although  the 
standard  of  requirement  has  not  been  generally  attained  to,  as  is 
shown  by  the  detailed  reports  of  the  inspectors. 


*  Kept.  Chief  of  Mass.  Dist.  Police,  1892,  p.  145. 


CHAPTER    XIX. 

DWELLINGS. 

IN  the  majority  of  the  dwelling  houses  in  this  country  no  special  ar- 
rangements for  ventilation  exist.  In  isolated  dwellings,  inhabited 
each  by  a  single  family,  and  having  a  large  area  of  external  surface 
in  proportion  to  cubic  contents,  including  all  farm  houses,  suburban 
villas,  and  the  majority  of  houses  in  villages  and  small  towns,  the 
problem  is  one  rather  of  satisfactory  heating  than  of  ventilation,  for 
the  arrangements  for  the  latter  may  be  very  simple. 

Let  us  take  as  an  example  a  suburban  residence  such  as  the  archi- 
tects in  our  northern  cities  are  often  called  upon  to  design,  a  building 
which  is  to  be  placed  on  an  elevated  site  for  the  sake  of  the  view,  and 
which  is  therefore  exposed  freely  to  the  cold  winds  of  winter. 

The  range  of  external  temperature  will  in  this  case  be  from  zero 
to  100°  F.,  and  the  prevailing  winds  from  the  southwest  in  summer, 
and  from  the  northeast  and  northwest  in  winter,  when  they  may  be 
strong  and  persistent  for  several  days,  with  the  temperature  below  the 
freezing  point. 

The  external  surface  of  the  house  will  be  broken  by  projecting 
bays,  giving  it  a  greater  extent  in  proportion  to  the  cubic  space  to  be 
warmed  than  is  usual,  while  the  rooms  facing  the  cold,  north  winds, 
present  special  difficulties,  so  far  as  securing  a  comfortable  tempera- 
ture at  all  times  is  concerned. 

In  such  a  building  it  will  be  true  economy  to  use  some  form  of 
central  heating  apparatus.  Neither  fireplaces  nor  stoves  merit  con- 
sideration as  the  principal  means  of  heating.  No  form  of  hot-air 
furnace  is  advisable  under  the  circumstances;  it  would,  in  fact,  require 
several  furnaces  if  this  form  of  heating  is  to  be  employed;  either  a 
hot-water  or  a  low-pressure  steam  apparatus  should  be  used.  The  fire- 
places in  each  room  will  provide  ample  ventilation  for  the  probable 
number  of  occupants,  and  this  ventilation  in  cold  weather  is  certain  to 
be  secured  by  the  amount  of  fresh  warm  air  which  must  be  introduced 
to  maintain  a  comfortable  temperature.  The  most  important  question 


DWELLINGS.  443 

to  be  decided  in  this  case  is  as  to  whether  the  radiators  and  hot-air 
flues  shall  be  concentrated  into  one  or  two  groups  near  the  center  of 
the  building,  or  whether  they  shall  be  placed  against  and  in  the  outer 
walls. 

The  difference  in  cost  between  these  two  plans  would  be  about  25  per 
cent,  in  favor  of  the  latter,  or  centralized  method.  The  absolute  cost 
in  either  case  will  depend  upon  whether  the  amount  of  radiating  surface 
is  to  be  sufficient  to  make  the  house  thoroughly  comfortable  in  the 
coldest  weather  and  during  cold  northeast  storms,  or  whether  such  sur- 
face is  to  be  calculated  only  for  temperatures  about  the  freezing  point, 
that  is,  for  the  average  demand,  relying  upon  the  fireplaces  and  grates 
as  auxiliary  sources  of  heat  on  those  days  when  the  apparatus  in  the 
cellar  is  insufficient.  If  the  latter  alternative  be  adopted,  the  cost  of 
the  apparatus  can  be  reduced  very  much,  yet  to  do  so  will  be  a  doubtful 
economy. 

The  general  principle  of  centralizing  the  heating  apparatus  is  that 
adopted  by  Drs.  Drysdale  and  Hayward  in  the  plans  which  they  give  in 
their  book  on  "  Health  and  Comfort  in  House  Building."  After  stating 
that  no  direct  admission  of  the  external  air  into  the  rooms  of  a  house 
can  be  borne  during  at  least  eight  months  of  the  year,  and  that  no  plan 
of  ventilation,  applicable  only  to  single  rooms,  can  supersede  the  neces- 
sity of  a  general  plan  for  the  whole  house,  they  say,  that  to  prevent 
waste  of  heat  "  care  should  be  taken  in  the  original  plan  of  the  house 
to  have  a  central  hall,  corridor,  lobby,  fresh-air  chamber,  or  vestibule, 
separate  from  the  stairs  lobby,  and  into  which  no  outer  door  should 
open.  The  back  door  should  open  into  the  scullery  or  kitchen,  or  some 
other  room  in  which  it  is  to  the  interest  of  the  servants,  for  their  own 
comfort,  to  keep  shut.  The  front  door  should  open  into  a  lobby  or 
vestibule  to  which  there  is  a  separate  access  from  the  servants'  apart- 
ments, without  their  going  through  the  central  hall  of  the  house  proper." 

From  this  central  hall,  kept  permanently  warm  and  serving  as  a 
warm-air  distributing  chamber,  they  direct  that  the  doors  of  all  rooms 
should  open,  and  they  bring  the  air  from  this  hall  into  the  several 
rooms  near  the  top  of  the  room  through  the  cornice.  The  plans  of 
houses  given  in  this  work  will  be  found  interesting  and  suggestive. 

The  removal  of  the  foul  air  in  these  houses  is  effected  by  the 
waste  heat  of  the  kitchen  fire,  the  air  passing  from  each  room  at  the 
ceiling  to  a  foul-air  chamber,  and  thence  down  and  behind  the  kitchen 
chimney  fire,  from  which  point  it  passes  up  the  chimney. 

Within  the  last  TO  years  hot-water  systems  of  heating  for  houses 
of  this  class  are  becoming  more  and  more  popular  in  the  Northern 


444 


DWELLINGS. 


States.  A  good  example  of  this  kind  of  work  is  the  residence  of  Prof. 
W.  M.  Sloane,  in  Princeton,  N.  J.,  the  heating  apparatus  of  which  is 
described  and  figured  in  The  Engineering  Recoi  d  vi  April  25,  1891. 

Figure  179  shows  the  arrangement  in  the  cellar  of  the  apparatus 
\  which  was  put  in  to  replace  a  furnace. 

A  is  a  Gurney  boiler,  No.  131,  with  804  square  inches  grate  area. 
F  F,  etc.,  are  flow,  and  R  R,  etc.,  are  2 -inch  return  pipes  to  the  direct 
radiators;  /and  r  are  2-inch  flow  and  return  pipes  to  the  Gold  radia- 
tors in  the  stacks  BCD  and  E  which  deliver  fresh  air  to  lower  floor 


fT- 


FlG.   179. 


rooms  through  registers  at  G  Gy  etc.  Stack  B  is  for  the  reception 
and  sitting  rooms;  C  for  the  hall,  and  D  and  E  for  the  drawing  room. 
ZTis  the  main  fresh-air  duct,  supplied  through  a  screen  and  sieve  in  a 
large  window.  /  /  /  are  branches  to  the  stacks,  and  J  and  K  Ky  etc., 
are  dampers;  the  former  admitting  outside  air,  and  the  latter,  tempered 
air  from  the  basement.  L  is  an  independent  fresh-air  duct  from 
another  window.  All  the  air  ducts  are  made  of  matched  pine  boards. 
The  direct  radiators  are  of  the  Bartlett  &  Hayward  and  Perfec- 
tion type,  except  a  large  wall  coil  in  the  children's  attic  play  room. 


DWELLINGS. 


445 


Figure  180  shows  the  position  of  the  radial  or  j?  in  the  library, 
where  it  is  set  between  the  bookcases  and  is  inclosed  by  a  brass 
screen  S. 

Figure  181  is  a  cross-section  of  Fig.  180  and  shows  the  polished 
metal  lining  T^that  is  intended  to  reflect  the  heat  into  the  room.  D 
is  a  small  door  commanding  the  valves. 

Figure  182  shows  the  wooden  base  B,  devised  to  inclose  the 
flow  pipe  to  one  of  the  chamber  radiators,  where  it  was  necessary  to 
connect  with  riser  C  and  avoid  running  under  the  floor.  The  piece  H 
was  fitted  into  the  corner  of  the  room  and  allowed  the  carpet  to  come 
to  its  outer  edges  without  cutting  around  the  pipe. 

The  total  radiating  surface,  exclusive  of  the  mains,  is  about  1,562 
square  feet. 


FIG.  180. 


Another  example  of  good  work  in  a  house  of  this  kind,  in  which 
more  than  usual  attention  has  been  given  to  ventilation,  is  the  residence 
of  Mr.  C.  S.  Onderdonk,  at  Wyncote,  Pa.,  of  which  the  following  de- 
scription and  plans  are  taken  from  The  Engineering  Record  of  July  23, 
1892  : 

The  system  is  one  of  indirect  hot-water,  with  ventilation  of  every 
room  into  a  central  stack  25  inches  in  diameter  in  the  clear,  the  draught 
in  which  is  induced  by  a  lo-inch  smoke  pipe  from  the  boiler.  All 
rooms  in  the  front  part  of  the  house  are  connected  to  this  central  stack 
either  directly  where  it  passes  through  such  rooms  or  adjacent  to  them, 
or  by  means  of  flues,  which  are  located  in  the  partitions,  proceed  to 
the  cellar  and  are  then  led  by  means  of  horizontal  ducts  into  the  base 
of  the  stack. 


446 


DWELLINGS. 


The  kitchen  or  frame  part  of  the  building  receives  its  ventilation 
by  means  of  a  brick  stack  y,  Fig.  183,  18  inches  in  the  clear  in  which 
an  8-inch  cast-iron  pipe  is  placed  which  induces  the  ventilation  in  that 
stack.  An  opening  is  made  immediately  over  the  kitchen  range  and 
one  at  the  ceiling  of  the  kitchen,  and  the  rooms  above  the  kitchen  are 
ventilated  into  this  stack. 


FIG.  181. 

A  B  C  JD  E  F  G  and  /  are  down-take  flues  exhausting  the 
foul  air  from  the  owner's  bedroom,  parlor,  sitting-room,  den,  etc.  The 
water  closet  on  the  second  floor  is  ventilated  by  means  of  a  duct  con- 
taining 12  square  inches  of  area,  which  rises  from  the  adjacent  partition, 
and  is  connected  to  the  central  ventilating  stack,  a  connection  also 


being  made  to  the  kitchen  stack  for  use  in  the  summer  months  when 
the  main  ventilating  stack  is  not  heated.  The  pipe  in  the  main  flue 
is  10  inches  in  diameter. 

The  valves  on  the  flow  pipes  to  each  radiator  stack  are  automatic- 
ally controlled  by  a  Johnson  electric  thermostat  in  the  rooms  respect- 


DWELLINGS. 


447 


ively  served  by  them.  The  radiators  have  no  air  valves,  but  are  fitted 
with  an  air  pipe  connected  to  an  open  riser  extending  in  the  main  ven- 
tilating stack  to  above  the  level  of  the  expansion  tank.  All  registers 
for  the  admission  of  warm  air  to  the  rooms  are  located  6  inches  below 
the  ceiling,  and  those  for  ventilation  are  set  on  the  opposite  side  of  the 
room  just  above  the  wash  board.  Each  stack  of  radiators  is  controlled 
in  addition  on  both  flow  and  return  by  Pratt  &  Cady  brass  gate  valves. 


Fl<;.  183. 

The  whole  system  of  piping  is  covered  with  magnesia  sectional 
covering.  In  addition  thereto  the  water  in  the  boiler  is  prevented 
from  reaching  the  boiling  point  by  means  of  a  Powers  limiting  device 
which  closes  off  the  draught  just  before  the  water  reaches  the  boiling 
point.  The  water  closet  in  the  laundry  in  basement  is  ventilated  into 
the  kitchen  stack.  The  galvanized-iron  flues  for  heating  when  erected 


448 


DWELLINGS. 


were  thoroughly  wrapped  with  asbestos  paper,  the  openings  in  the  wall 
being  thoroughly  parged  for  the  reception  of  the  flue. 

Fresh  cold  air  is  admitted  from  out  doors  through  windows  K  K 
and  /,  the  two  former  of  which  are  opposite  each  other,  and  are  so 
arranged  on  opposite  sides  of  the  house  that  either  one  may  be  closed 
and  the  supply  be 'drawn  through  the  other  one  according  to  conditions 
of  sunshine,  shadow  and  prevailing  winds.  The  branches  from  the 


184. 

supply  ducts  to  the  radiator  stacks  underneath  the  latter  and  so  hidden 
by  them,  are  here  shown  dotted. 

In  Figs.  185  and  186,  the  plans  of  the  first  and  second  floors, 
the  fresh  and  foul-air  flues  are  marked  M  N  and  H,  respectively, 
to  indicate  which  floors  they  serve.  All  registers  are  marked  R, 
with  the  size. 


DWELLINGS. 


449 


The  system  has  been  in  operation  an  entire  winter,  and  has  proved 
satisfactory. 

Figures  187,  188,  i8<>,  190  and  191  show  plans  of  the  residence 
of  Gen.  A.  C.  McClurg,  in  Chicago,  illustrating  the  system  of  hot- 
water  heating  put  in  by  the  L.  H.  Prentice  Company,  of  that  city,  to 
which  I  am  indebted  for  the  plans  and  for  the  following  description. 


FIG.  185. 


The  apparatus  is  a  low-temperature  open-tank  hot-water  heat- 
ing system,  designed  to  accomplish  its  work  with  a  water  temperature 
not  exceeding  180  degrees.  The  method  of  heating  is  by  indirect 
radiation  in  the  principal  rooms  and  halls  of  the  dwelling,  the  minor 
rooms  being  warmed  by  direct  radiation. 


45° 


DWELLINGS. 


Special  horizontal  wrought-iron  tube  radiators  are  used  for  the 
indirect  surfaces,  and  the  usual  ornamental  cast-iron  vertical  loop 
radiators  are  used  for  the  direct  radiation — the  amount  of  surface  in 
superficial  square  feet  being  indicated  on  each  plan.  The  indirect 
radiators  are  enclosed  in  chambers  of  brick,  connected  with  a  system 


FIG.  186. 


of  underground  air  ducts,  as  shown  on  the  subcellar  plan.  Before  the 
air  is  introduced  into  the  ducts,  it  is  first  admitted  into  outside  settling 
chambers,  for  the  purpose  of  depositing  the  dust,  etc.  There  are  two 
air  inlets,  each  of  which  is  controlled  by  an  automatic  damper,  operated 
by  a  device  which  expands  and  contracts  according  to  the  heat  of  the 


DWELLINGS. 


451 


water,  so  that  if  the  circulation  is  at  any  time  stopped,  the  danger  of 
freezing  is  reduced  to  a  minimum. 

The  underground  ducts  are  built  of  brick,  laid  in  Portland  cement, 
the  top  being  covered  with  stone  slabs.  Provision  is  also  made  for 
taking  the  air  from  within  the  building  at  such  times  as  the  house  is 
not  occupied.  This  also  permits  of  access  to  the  ducts,  all  of  which 
are  large  enough  to  admit  the  body  of  a  boy  or  man. 


5. _» Trencn  forRetum  Pipe 

9  U 


FOUNDATION   PLAN 


FIG.  187. 


Fireplaces  are  relied  upon  for  ventilation  in  this  house,  except  in 
the  laundry  and  in  the  second-story  boudoir,  which  are  ventilated  by 
independent  tin  flues,  which  find  their  termination  above  the  roof  of 
the  building  in  appropriate  ventilating  cowls  or  caps.  All  of  the  fire- 
place chimneys  are  high  above  the  rest  of  the  building,  and  efficient 
draught  is  thus  assured. 


45  2 


DWELLINGS. 


The  subcellar  plan  indicates  the  location  of  the  various  ducts,  and 
also  shows  trenches  in  which  the  return  pipes  are  run  back  to  boiler. 
The  basement  plan  shows  the  location  of  the  various  flow  pipes, 
boilers  and  indirect  radiators.  The  first,  second  and  third-floor  plans 
show  the  location  of  the  various  registers  and  radiators,  also  ventilat- 
ing openings.  The  return  pipes  are  not  shown,  as  they  are  identical 


FIG. 


with  the  flow  pipes,  except,  of  course,  that  they  are  under  the  floor 
instead  of  at  the  ceiling.  All  risers  and  radiators  are  properly  valved 
for  shutting  off  in  case  of  repairs  or  changes. 

There  are  two  boilers  used  in  this  work,  being  two  i2-section 
Richmond  boilers,  having  18  square  feet  of  grate  surface,  and  about 
500  square  feet  of  heating  surface. 


DWELLINGS. 


453 


The  heating  apparatus  is  also  operated  in  connection  with  the 
Johnson  electric  service,  which  controls  the  dampers  on  the  boilers, 
and  also  individually  regulates  the  temperature  of  the  several  rooms, 
thus  correcting  any  slight  discrepancies  in  the  adjustments  of  the 
various  parts  of  the  heating  system. 

Figures  192-195  illustrate  the  system  of  hot-water  heating  em- 
ployed in  the  residence  of  Mr.  W.  A.  Fuller,  of  Chicago,  by  the  L.  H. 


FIG.  189. 

Prentice  Company,  to  which  I  am  indebted  for  these  plans.  The 
plans  are  self-explanatory.  The  foul  air  is  removed- from  the  living 
rooms  by  fireplaces. 

Let  us  now  take,  as  a  contrast  to  buildings  of  this  kind,  in  which 
the  heating  is  the  most  difficult  part  of  the  problem,  a  private  resi- 
dence of  the  better  class,  situated  in  a  block  in  one  of  our  large  cities. 
Such  a  house  will  not  be  exposed  to  cold,  bleak  winds,  and  is  in  the 


454 


DWELLINGS. 


most  favorable  conditions  for  heating,  being  exposed  to  the  external 
air  on  two  sides  only. 

On  the  other  hand,  its  ventilation  will  be  more  likely  to  be  unsatis- 
factory, and  will  require  more  attention  than  will  that  of  the  country 
house. 

The  external  air  is  not  as  pure;  it  contains  dust  of  all  kinds — 
soot,  street  sweepings,  etc.;  the  air  in  the  house  is  liable  to  special 


CEILING  -IOfT -6IN 


FIG.  190. 


contaminations  by  leakage  of  gas  into  its  cellar  or  basement;  and  it 
has  happened  that  offensive  gases  have  passed  directly  through  party 
walls  from  one  dwelling  to  another.  The  great  cost  of  the  ground 
leads  to  gaining  space  by  increase  in  height,  while  every  additional 
story  adds  to  the  cost  and  difficulty  of  providing  equable  and  satis- 
factory heating  and  ventilation. 


DWELLINGS. 


455 


FIG.  191. 


BARN 


PLAT  or  GROUNDS      * 
BOILERS 'IN 'BARN       \ 


FIG.  192. 


HOUSE 


45  6 


DWELLINGS. 


In  a  tall  building,  where  all  the  rooms  open  directly  into  the  stair- 
case hall,  and  no  provision  is  made  for  dividing  this  hall  and  staircase  upon 
the  several  stories,  so  as  to  prevent  the  free  communication  of  the  air 


Main  Supply  from 
!  Boilers  in  Barn. 


FIG.  i93. 


in  it,  the  result  is  that  the  hall  is  liable,  by  leakage  from  above,  or  by 
the  opening  of  a  window  in  the  upper  story,  to  become  a  ventilating 
shaft,  which  will  fhterfere  with  the  proper  working  of  the  chimney  or 


DWELLINGS. 


457 


ventilating  flues  within  the  ro'oms.    In  such  buildings,  in  cold  weather, 
it  will  often  be  found  that  the  upper  stones  have  a  temperature  several 


degrees  higher  than  the  lower,  and,  if  the  house  be  heated  by  indirect 
radiation,  that  to  secure  comfort  in  the  parlor  and  dining  room,  the  bed- 


458 


CITY    DWELLINGS. 


rooms  are  made  too  hot.  It  is  especially  difficult  in  such  houses  to 
prevent  the  odors  and  steam  from  the  kitchen  and  laundry,  which  are 
usually  placed  in  the  basement,  from  being  unpleasantly  perceptible  in 
the  halls  and  upper  stories. 

On  the  other  hand,  both  the  fresh  and  the  foul-air  flues  will  be, 
for  the  most  part,  on  inner  walls,  where  their  operation  is  not  liable  to 
be  interfered  with  by  winds  or  cold. 

One  method  of  arranging  such  a  city  dwelling  is  shown  in  the 
accompanying  illustration  (Fig.  196).  The  plans  of  the  first  and 


SECOND  FLOOR 


CEILING  n'-o" 


FIG.  195. 

fourth  floors  are  not  given,  as  they  are  not  necessary  to  an  understand- 
ing of  the  system  of  heating. 

The  essential  feature  of  this  house  is  the  central  hall,  occupying 
the  whole  width  of  the  building,  and  well  lighted  from  above  by  a 
large  skylight. 

It  will  be  seen  that  a  part  of  this  hall  is  cut  off  for  a  private  or 
back  staircase  and  a  lift,  and  that  upon  the  parlor  and  upper  floors  it 
forms  a  part  of  the  main  suite  of  rooms.  At  the  skylight  is  an  open- 
ing having  an  area  of  2^  square  feet,  always  open,  and  when  the 
heating  apparatus  is  in  operation  there  is  a  steady  upward  current 


CITY    DWELLINGS. 


459 


from  the  basement  through  the  staircase  well,  which  is  just  perceptible 
to  the  hand,  being  between  i  and  2  feet  per  second. 

The  plans  are,  for  the  most  part,  self-explanatory. 

The  heating  is  by  steam  at  a  very  low  pressure,  the  boiler  being 
entirely  out  of  the  house  under  the  front  pavement.  The  heating  coils 
are  divided  into  three  groups,  as  shown  in  basement  plan,  having  in  all 
about  2,200  feet  of  i-inch  pipe.  Before  reaching  the  coils  the  incorrr 


FIG  ^.-DESCRIPTION  OF  PLANS. 


A.— Fresh-air  inlet  flues. 

B. — Boiler,   separated  from  house  by  open 

area. 

C.  —  Heating  coils. 
D.— Flue  to  hall  and  second  story. 
E.— Flue  to  third-story  bedroom. 
F. — Flue  to  dining  room. 


K. — Chandelier  with  vent  to  convey  pro- 
ducts of  gas  combustion. 

L.— Kitchen  heated  flue. 

H. — Chimney  of  boilers  with  cast-iron  flue 
into  which  gas  lights  are  ventilated. 

A*.— Registers 

R  ^.—Bathroom. 


ing  air  is  filtered  by  being  drawn  through  sheets  of  cotton  wadding 
placed  between  wire  frames.  The  results  are  stated  to  be  extremely 
satisfactory.  The  greater  part  of  the  ventilation  is  effected  by  the  cen- 
tral hall  and  skylight.  The  amount  of  air  supply  is  very  large,  and  no 
difficulty  has  been  experienced  in  having  open  fires  in  open  fireplaces 
when  desired.  The  chandeliers  in  the  parlor  and  dining  room  contribute 


t6o 


CITY    DWELLINGS. 


to  the  ventilation,  as  shown  on  the  plans,  and  it  is  stated  that  20 
persons  can  smoke  in  the  dining  room  without  causing  the  least 
accumulation  of  smoke.  Similar  ventilation  is  supplied  to  the  chande- 
liers in  the  library  and  other  rooms  upon  the  third  floor. 

Of  course  the  flues  with  which  these  chandeliers  communicate 
must  pull  against  the  great  central  staircase  flue,  but  the  results  re- 
ported are  so  satisfactory  that  it  is  evident  that  the  amount  of  air  supply 
is  so  large  as  to  be  ample  for  all  the  outlets.  The  amount  of  fuel  used 
must  be  relatively  large — that  is,  large  as  compared  with  what  would 
be  required  to  heat  the  same  house  with  the  same  apparatus  if  only  the 
ordinary  amount  of  ventilation  were  provided. 

Figure  197  is  a  plan  of  another  city  house  in  a  block.  This  is  the 
common  arrangement  in  such  rows  of  dwellings,  the  characteristic 
feature  being  a  narrow,  rather  dark  hall  extending  from  front  to  rear, 
on  one  side  of  the  building.  This  hall  contains  the  stairway,  and  in 
many  cases  a  water  closet.  The  annexed  illustration  gives  the  main 
floor  plan  of  such  a  residence,  which  is  superior  to  the  average  in  size. 

This  house  is  heated  by  two  furnaces,  the  locations  of  which  are 
shown  in  dotted  outline  and  this  mode  of  heating  will  prove  entirely 
satisfactory,  provided  only  that  the  fresh-air  ducts  and  the  heating 
surfaces  are  made  large  enough  to  prevent  the  possibility  of  the  air  as 
it  leaves  these  surfaces  having  a  higher  temperature  than  140°  F. 

The  best  way  to  arrange  the  ventilation  of  such  a  house  as  this 
would  be  upon  the  principles  indicated  by  Drysdale  and  Haywood, 
and  for  this  purpose  more  space  should  be  given  in  connection  with 
the  kitchen  chimney. 

With  fireplaces  and  separate  flues  therefrom  in  all  living  rooms, 
there  will  be  little  trouble  about  ventilation  at  all  times,  when  the  ex- 
ternal temperature  is  below  40°  F.,  for  there  will  then  be  a  steady  cur- 
rent up  each  flue,  provided  the  fresh-air  supply  be  sufficient,  which 
last  must  be  the  case  if  the  room  is  satisfactorily  warmed.  The 
special  difficulty  in  ventilation  in  a  house  like  this,  and  one  of  the 
chief  dangers  to  health,  is  due  to  the  pollution  of  the  air  of  the  hall 
and  sleeping  rooms  from  the  plumbing  arrangements. 

With  a  dark  water  closet  near  the  center  of  the  house,  it  is 
necessary  to  take  special  precautions  to  secure  its  satisfactory  condition 
at  all  times.  The  methods  of  doing  this,  so  far  as  plumbing  work  is 
concerned,  do  not  fall  within  the  scope  of  this  work,  but  I  must  insist 
upon  the  necessity  of  a  satisfactory  ventilation  of  the  closet  itself.  The 
surest  mode  of  effecting  this  is  by  a  shaft  passing  up  and  through  the 
roof  and  suitably  capped,  as  I  shall  hereafter  explain,  in  which  shaft  a 


CITY    DWELLINGS. 


461 


FIG.  197. 


462  CLOSETS. 

steady  aspirating  force  is  to  be  exerted  by  means  of  a  gas  jet,  which 
may  at  the  same  time  serve  to  light  the  closet. 

This  shaft  should  take  its  air  supply  from  beneath  the  seat  of  the 
closet,  and  it  will  be  well  to  place  in  it  the  soil  pipe,  which  I  take  for 
granted  is  also  to  be  continued  up  through  the  roof. 

The  area  of  this  ventilating  shaft  should  be  about  30  square 
inches,  if  it  passes  straight  up  without  bends  or  corners  and  does  not 
contain  the  soil  pipe.  The  portion  of  the  flue  within  the  closet  can  be 
best  constructed  of  galvanized  iron,  and  should  be  fitted  as  a  lantern 
at  the  point  where  the  gas  jet  is  brought  into  it.  This  gas  jet  should 
have  a  stop  so  arranged  that  it  can  never  be  turned  entirely  out  with- 
out the  use  of  tools,  although  it  may  be  reduced  to  a  very  small  flame. 

The  warmer  the  weather,  especially  if  it  is  still,  the  more  heat  will 
be  needed  from  the  jet  to  secure  satisfactory  ventilation.  The  air 
supply  for  the  closet  should  be  taken  from  the  hall  through  a  transom 
or  louvered  openings  in  the  top  of  the  door,  thus  making  the  closet  the 
bottom  of  an  air  shaft  for  ventilating  the  hall. 

I  wish  it  to  be  clearly  understood  that  the  arrangement  is  recom- 
mended only  for  those  houses  which  have  their  drainage  properly 
arranged,  and  where  the  closet  is  not  against  an  outside  wall.  The 
use  of  the  gas  jet  is  advised,  because  it  is,  upon  the  whole,  the  cheapest 
method  of  securing  a  constant  upward  current  under  such  circum- 
stances. There  are  various  ways  of  arranging  the  gas  jet,  some  of 
which  are  patented,  but  these  do  not  seem  to  me  to  require  special 
comment. 

Even  in  houses  having  special  provisions  for  ventilation,  the  closets 
for  clothing  are  usually  not  arranged  for  any  circulation  of  air.  This 
should  be  provided  for  by  openings  at  the  floor  and  near  the  ceiling, 
which  openings  may  be  covered  by  cotton  batting  or  cheese  cloth 
filtering  frames  if  the  housekeeper  objects  to  simple  openings  on  the 
ground  of  their  giving  ingress  to  moths.  Soiled  clothing  or  bedding, 
or  bags  containing  them,  should  not  be  placed  in  any  closet. 

Figure  198  is  a  basement  plan  of  the  house  of  Mr.  S.  L.  George, 
at  Watertown,  N.  Y.,  showing  flow  and  return  mains  of  the  system  of 
hot-water  heating,  the  full  lines  indicating  flow  and  the  broken  ones 
the  returns.  The  parlor,  drawing  room  and  main  hall  are  heated  by 
indirect  radiation,  the  rest  of  the  house  by  direct  radiators  and  by  fire- 
places which  act  as  outlets.  The  riser  flow  lines  to  direct  radiators 
are  indicated  by  full  oblique  lines  at  A  B  C  D  and  £,  At  F  G  and 
jfifare  connections  to  first-floor  radiators.  The  direct  radiators  at  the 
different  risers  have  total  surfaces  for  their  respective  cubic  feet  of 


DWELLINGS. 


463 


space  heated  as  follows:  At  A  is  a  tower  room  having  1,287  cubic  feet 
air  space,  with  an  exposure  to  the  west.  It  has  $y2  square  feet  radia- 
ting surface  per  100  cubic  feet  air  space.  At  B  is -a  chamber  having 
2,376  cubic  feet  air  space,  with  northern  and  eastern  exposures.  It  has 


FIG.  199.  FIG.  200. 

3  square  feet  radiating  surface  per  100  cubic  feet  of  air  space.  At  C 
is  a  bathroom  containing  648  cubic  feet  air  space,  with  an  eastern  ex- 
posure. This  has  4%  square  feet  radiating  surface  per  TOO  cubic  feet 
air  space.  At  D  is  a  chamber  containing  2,295  cubic  feet  air  space, 


464  DWELLINGS. 

having  a  southern  and  western  exposure,  with  2^  square  feet  radiating 
surface  to  100  cubic  feet  air  space.  At  E  is  a  chamber  having  1,872 
cubic  feet  air  space,  with  exposure  to  the  west,  north  and  south,  with 
3  square  feet  radiating  surface  per  100  cubic  feet  airspace.  At  F  is  a 
bathroom  containing  680  cubic  feet  air  space,  having  exposures  to  the 
south  and  east.  It  has  4^/2  square  feet  radiating  surface  per  100 
cubic  feet  air  space.  At  G  is  a  butler's  pantry  containing  700  cubic 
feet  air  space,  with  a  western  exposure.  It  has  4^  square  feet 
radiating  surface  per  TOO  cubic  feet  air  space.  At  H  is  a  chamber 
having  2,560  cubic  feet  air  space,  with  an  exposure  to  the  east,  and  3 
square  feet  radiating  surface  to  100  cubic  feet  air  space. 

I J  arid  K  are  indirect  radiator  stacks,  each  of  150  square  feet  of 
surface  to  warm  about  2,975  total  cubic  feet  of  air;  L  L  are  fresh-air 
conduits;  M  is  a  Richardson  &  Boynton  Company  No.  28  "  Perfect  " 
boiler,  with  676  square  inches  of  grate  area;  N  is  the  smoke  flue;  .P./3 
are  syphons  intended  to  promote  the  circulation  in  the  indirect 
stacks. 

Figure  199  shows  the  arrangement  of  syphons  P  P\  O  is  a 
vent  pipe  to  the  expansion  tank.  Figure  200  shows  the  arrangement 
of  indirect  stacks  J  and  K,  and  expansion  tank  T.  Cold  air  is  re- 
ceived from  duct  L  in  the  cold  chambers  Q,  and  passing  through  the 
extended  surface  radiators  S,  passes  into  the  hot  chamber  U,  and  is 
thence  delivered  through  the  floor  radiator  R* 

Figures  201-203  show  the  hot-water  heating  apparatus  in  the 
house  of  Mr.  W.  H.  Carrick,  of  Toronto,  Canada,  which  is  typical  of 
the  system  of  piping  largely  followed  in  Upper  and  Lower  Canada  in 
the  warming  of  buildings  by  hot-water  circulations. 

The  plant  has  proved  ample  for  the  warming  of  a  fairly  well  built 
wooden  structure  with  water  ranging  from  120°  to  190°  F.,  according 
to  the  state  and  requirements  of  the  weather  outside. 

It  will  be  noted  that  the  cubic  contents  of  rooms  are  marked,  the 
position  of  heaters  shown,  and  their  sizes  marked,  the  figure  attached 
to  each  indicating  the  number  of  "  Bundy  "  loops,  each  loop  being 
nominally  3%  square  feet  ot  heating  surface  in  the  hot-water  radiator. 

The  heights  in  the  clear  of  floors  are,  for  the  principal  or  first 
floor,  10  feet  6  inches;  the  second  floor,  9  feet,  and  the  third  floor,  or 
attic,  8  feet. 

The  sizes  of  the  mains  and  floor  pipes  are  marked  on  the  plans, 
and  the  boiler  is  a  No.  25  Gurney;  the  consumption  of  anthracite  coal 

*  From  The  Engineering  Record,  November  21,  1891. 


DWELLINGS. 


465 


for  a  season  being  seven  tons  and  just  about  100  pounds  per  day  in 
cold  weather;  the  climate  of  Toronto  differing  very  little  from  the 
cities  of  northern  New  York,  Ohio,  Michigan,  western  Pennsylvania 
and  the  Eastern  States.  This,  then,  may  be  taken  somewhat  as  a  guide 
to  the  plant  and  its  maintenance  for  a  $5,000  house  on  a  20-foot  city 
lot  in  the  new  district  of  New  York  or  in  Brooklyn. 


t.V 


FIG.  201. 


Figure  203  shows  the  skeleton  apparatus,  and  a  reference  to  the 
plans  will  show  its  relation  to  the  house.  The  boiler  is  in  the  front 
cellar.  The  radiators  marked  A  in  the  diagram  are  on  the  principal 
floor,  those  marked  B  are  on  the  second  floor,  and  the  ones  marked  C 
are  on  the  top  floor. 


466 


.DWELLINGS. 


The  circuit  No.  i  starts  from  the  boiler  il/z  inches  in  diameter, 
runs  along  with  the  rest  of  the  pipes  to  near  the  pantry,  where  it  turns 
upward  and  runs  through  the  partition  to  the  top  floor,  where  it 
comes  out  and  branches  to  the  two  radiators  and  expansion  tank. 

Circuit  No.  2  starts  from  the  boiler  2  inches,  and  continues  on  to 
the  end  of  pantry  where  it  has  a  tee  2"xi^"xi%";  one  branch  of  which 


PLANS 

SHOWING  HOT  WATER  Pip£$ 
•IN  THE  RESIDENCE  or 


FIG.     202. 

goes  along  parallel  with  side  of  pantry  to  pantry  door  and  then  goes 
up  through  the  partition  and  feeds  sewing  room,  bathroom,  and 
upstairs  hall.  The  other  branch  runs  straight  to  the  back  end  of 
house,  and  up  through  the  kitchen  to  the  nursery,  where  it  heats  the 
radiator  near  the  window.  It  may  seem  strange  that  this  break  was 
made  in  this  way,  but  it  was  found  when  split  at  the  point  where 
the  first  pipe  went  up  that  the  circulation  was  very  sluggish,  and  that 


DWELLINGS. 


the   nursery   radiator   did    not   heat   properly, 
running  the  two  pipes  parallel  to  this  point. 


467 
hence   the   change  of 


LJJ 
Q 
!n  IL 

go 

Ul 

I 
h 

Z 


£  S 


(3      ti] 

*  s 


if 


U      K 

K  a, 


FIG.  203. 


I 
iJ  f 


Circuit  No.  3  starts  from  boiler  il/2  inches  in  diameter,  and  heats 
the  six-pipe  radiator  in  the  den,  and  then  continues  i#  inches  on  to 
one  radiator  in  dining  room  which  has  14  loops. 


468  DWELLINGS. 

Circuit  No.  4  starts  from  boiler  2  inches  in  diameter,  and  branches 
to  a  i>£-inch  pipe  to  the  lower  hall,  and  i^  inches  to  parlor. 

Circuit  No.  5  breaks  at  the  boiler  into  two  i^-inch  pipes,  one 
going  to  front  chamber  where  it  heats  the  14  loops,  and  the  other  to 
the  back  chamber  (second  floor),  where  it  heats  the  eight  loops. 

The  flow  and  return  pipes  of  a  circuit  are  exactly  alike  in  size  and 
almost  identical  in  the  manner  of  being  run.  The  pipes  are  near  the 
ceiling,  with  a  pitch  of  about  i  inch  in  10  feet. 

Each  radiator  has  an  angle  valve  on  the  inlet  end  and  an  air  cock 
in  the  top  chamber.  Although  air  collects  in  this  chamber  a  neglect 
of  a  week  is  not  sufficient  to  affect  the  flow  of  the  water.  The  dotted 
lines  in  the  plan  indicate  pipes  under  floor  or  in  partitions,  while  the 
dotted  lines  in  the  diagram  indicate  the  return  flow  pipe.  The  pipes 
through  the  cellar  are  covered  with  a  plastic  non-conductor.* 

In  a  recent  number  of  the  Genie  Civil  of  Paris,  M.  Somasco  de- 
scribes a  house  constructed  at  Creil,  France,  in  accordance  with  the 
views  of  Leeds  and  of  M.  Trelat  that  the  walls  should  be  warmed  and 
the  fresh  air  admitted  cold. 

This  house  is  a  separate  dwelling  of  two  stones,  with  large  hall 
and  attic.  The  walls  are  hollow,  having  a  total  thickness  of  about  22 
inches,  the  exterior  wall  being  about  9  inches,  and  the  interior  of  4 
inches,  with  a  hollow  space  of  from  8  to  9  inches. 

The  walls  of  the  basement  are  solid  ;  at  their  upper  part  near  the 
ceilings,  all  around  the  interior,  are  openings  into  the  hollow  wall 
space  ;  the  interior  partition  surrounding  the  basement  forms  a  large 
passage  closed  in  front  of  the  openings  into  the  hollow  walls.  This 
passage  is  in  direct  communication  with  the  external  air.  On  all  sides 
of  the  house  are  large  openings.  In  the  interior  of  the  passage  there 
are  heating  pipes  containing  warm  water  for  the  purpose  of  heating 
the  air  ;  this  warm  water  being  circulated  in  the  hollow  wall,  heats  also 
the  whole  establishment.  The  external  air  is  admitted  throughout 
into  the  different  rooms  by  a  natural  orifice  without  any  heating,  and 
is  taken  out  by  chimneys  for  each  department. 

Figure  204  is  a  plan  of  the  basement  and  Fig.  205  is  a  section 
showing  the  mode  of  admission  of  fresh  air  through  the  outer  wall  and 
the  mode  in  which  the  heated  air  enters  the  space  between  the  walls 
above  the  basement. 

The  temperature  of  the  air  in  the  interior  of  the  walls  varies  from 
45°  to  50°  C.  ;  under  these  conditions  the  temperature  of  the  walls  on 
their  internal  surface  is  from  30°  to  36°  C.  in  the  lower  story  ;  to 
*  The  above  description  is  taken  from  The  Engineering  Record. 


DWELLINGS. 


469 


the  touch  the  wall  gives  no  sensation  of  heat,  whatever  may  be  the 
variations  of  the  external  temperature.  That  of  the  interior  surface  of 
the  walls  never  varies  more  than  6  degrees.  The  temperature  of  the 
wall  decreases  about  i  degree  per  meter  of  height.  From  above  the 
second  story  the  air  passes  out  into  halls  at  a  temperature  of  40°  C. 
The  location  of  the  house  is  a  damp  one,  but  the  interior  is  dry,  and 
the  house  is  said  to  be  very  comfortable.  There  is  never  any  need  for 


M 


FIG.  204. 

supplementary  heating  in  the  fireplaces,  and  the  supply  of  fuel  required 
is  said  to  be  small. 

In  a  cold  climate  however  the  loss  of  heat  through  the  outer  wall 
would  involve  a  heavv  cost  for  fuel. 


FIG. 


205. 


In  the  preceding  remarks  upon  the  heating  and  ventilation  of 
dwelling  houses,  only  such  buildings  have  been  kept  in  view  as  archi- 
tects are  usually  called  upon  to  plan  or  construct — namely,  the  larger 
and  better  class  of  city  residences  and  suburban  villas. 

it  has  been  pointed  out  that  the  problem  in  such  houses  is  com- 
paratively simple;  the  difficulties  relating  mainly  rather  to  warming 
than  to  ventilation,  although  it  must  be  confessed  that,  simple  as  it  is, 


470  DWELLINGS. 

it  has  been  in  the  majority  of  such  houses  not  only  unsolved,  but  not 
even  supposed  to  exist.  But  what  shall  we  say  of  the  houses  with 
which  architects  have  nothing  to  do,  but  which  contain  the  immense 
majority  of  cur  people,  both  in  cities  and  in  the  country?  Taking 
these  as  we  find  them,  what  should  we  recommend  to  their  owners  or 
tenants  as  desirable  improvements  ? 

Let  us  first  take  an  extreme  case,  such  as  a  room  in  a  tenement 
house  which  is  occupied  by  a  family  of  four  or  five  persons.  The 
room,  about  14  feet  square  and  10  feet  high,  must  serve  as  a  kitchen, 
living  room  and  bedroom.  It  is  heated  by  a  small  cooking  stove,  has 
one  window,  and  one  door  opening  into  an  interior  hall,  which  is  dark 
and  dirty. 

Every  pound  of  fuel  is  a  matter  of  importance,  and  every  chink 
and  cranny  at  which  cold  fresh  air  might  enter  is,  as  far  as  possible, 
stopped  up.  During  cold  weather,  and  under  ordinary  circumstances, 
it  is  practically  impossible  to  do  much  toward  improving  the  ventila- 
tion of  this  room;  impossible,  not  because  of  mechanical  difficulties, 
but  because  the  occupants  do  not  want  ventilation,  which  will  either 
make  the  room  cold  or  increase  the  expense  for  fuel.  Occasionally, 
however,  in  case  of  sickness,  the  doctor  insists  on  having  some  fresh 
air  for  his  patient,  and  it  is  well  to  know  what  can  be  done  to  secure 
this.  Anyone  who  understands  the  general  principles  of  ventilation 
and  has  a  little  mechanical  ingenuity  will  find  no  difficulty  in  this  re- 
spect. To  secure  a  fresh-air  inlet,  for  instance,  raise  the  lower  sash 
of  the  window  from  4  to  6  inches,  by  placing  underneath  it  a  piece  of 
board  which  will  just  fill  the  opening  thus  created.  This  makes  a 
fresh-air  inlet  at  the  point  of  junction  of  the  lower  and  upper  sashes, 
and  the  incoming  stream  of  air  will  be  directed  upward,  so  that  it  will 
not  usually  cause  an  unpleasant  draught. 

The  same  effect  can  be  obtained  by  removing  one  of  the  upper 
panes  in  the  upper  sash  and  fitting  to  it  a  sort  of  hopper  or  funnel 
made  of  tin  or  pasteboard,  so  arranged  as  to  direct  the  current  of  air 
to  the  ceiling. 

The  outlet  must  be  obtained  by  the  chimney  flue,  the  simplest 
plan  being  to  make  an  opening  about  9  inches  in  diameter  into  the  flue, 
and  so  arrange  a  valve  of  paper,  in  a  pasteboard  tube  or  bit  of  stove 
pipe  placed  in  this  opening,  that  a  reverse  current  will  be  prevented, 
being  a  rough-and-ready  application  of  Arnott's  valve.  Physicians  of 
the  poor,  and  those  engaged  in  charitable  work,  as  well  as  all  nurses, 
should  be  prepared  to  devise  such  simple  methods  as  these  with  little 
or  no  cost,  and  in  this  connection  attention  is  invited  to  the  essay  on 


DWELLINGS.  471 

"An  Effective  and  Ready  Method,  of  Ventilating  Sick  Rooms,"  etc., 
for  which  a  prize  was  awarded  by  the  Massachusetts  Medical  Society 
to  X.  Y.  Z.,  in  187  r,  and  which  will  be  found  in  the  papers  of  that 
society  for  7872. 

Care  must  be  taken  to  make  the  tubes  of  sufficient  size,  for  some 
very  absurd  ideas  have  been  urged  in  favor  of  the  use  of  small  pipes. 
For  instance,  Dr.  George  Wyld,  one  of  the  Committee  on  Sanitary 
Science  at  the  Society  of  Arts,  in  a  paper  presented  to  the  Social 
Science  Association  in  1858,  says:  "  I  roughly  estimate  the  diameter 
of  the  required  piping  necessary  to  ventilate  any  given  apartment  at 
about  a  multiple  of  the  diameter  of  the  trachea  or  main  air  passage 
from  the  lungs  of  those  present.  For  instance,  to  ventilate  a  room  con- 
taining generally  eight  individuals,  a  pipe  about  2  inches  in  diameter 
would  be  sufficient."  Upon  such  teaching  as  this,  it  is  not  to  be 
wondered  at  that  architects  and  engineers  should  put  a  low  value, 
especially  as  Dr.  Wyld  relies  on  his  little  tube  exclusively  and  makes 
no  provision  whatever  for  the  entrance  of  fresh  air. 

Passing  from  the  tenement  room,  let  us  take  the  small  house  of 
from  three  to  six  rooms,  occupied  by  a  single  family. 

Such  houses  in  this  country  are  usually  heated  by  some  form  of 
stove,  and  have  no  special  means  of  any  kind  for  the  inlet  of  fresh  or 
the  exit  of  foul  air.  The  rooms  are  small,  the  hall,  if  there  is  one,  is 
not  heated,  and  the  bedrooms  are  warmed  only  on  special  occasions, 
as  in  case  of  sickness. 

The  house  will  be  of  brick,  with  9-inch  walls  and  plenty  of  cracks 
from  shrinkage  about  doors  and  windows  and  at  the  washboards.  The 
amount  of  air  which  would  enter  through  these  cracks,  and  directly 
through  the  walls  of  the  house  were  it  not  in  a  block,  would  be  nearly 
enough  for  ventilation  purposes.  The  permeability  of  the  walls  is, 
however,  often  destroyed  by  papering  them.  To  save  labor  as  well  as 
fuel,  usually  but  two  fires  will  be  kept  up,  one  in  the  kitchen  and  one 
in  the  sitting  room,  and  in  very  many  houses  of  the  kind  we  are 
speaking  of,  the  kitchen  fire  is  the  only  one  to  be  found  during  the 
greater  part  of  the  time. 

Economy  in  fuel  and  labor  is  here  the  first  consideration,  and  to 
secure  these  results  many  different  patterns  of  stoves  have  been  de- 
vised, but  with  regard  to  the  relative  merits  of  these  various  patterns 
we  have  singularly  little  information.  During  the  last  10  years,  how- 
ever, a  number  of  attempts  to  secure  the  introduction  of  fresh  warm 
air  by  means  of  the  stove  have  been  made,  and  there  are  now  on  the 
market  several  patterns  of  ventilating  stoves  devised  for  this  purpose. 


472  STOVES. 

So  far  as  economy  in  fuel  and  labor  is  concerned,  when  anthracite 
coal  is  to  be  used,  the  most  approved  modern  patterns  of  base-burning 
stoves  give  excellent  results  if  connected  with  the  proper  flues,  but  as 
usually  set  up  they  not  only  give  no  aid  to  ventilation,  but  often  are 
direct  sources  of  contamination  of  the  air  of. the  room  with  the  gaseous 
products  of  combustion.  In  order  to  secure  the  greatest  possible 
utilization  of  all  the  heat  produced  in  a  stove,  it  is  necessary  that  the 
/•  smoke  shall  pass  into  the  chimney  flue  at  the  lowest  temperature  con- 

sistent  with  securing  sufficient  and  regular  draught,  and  to  this  end  much 

may  be  effected  by  such  contrivances  as  sheet-iron  drums,  etc.,  which 
will  utilize  the  waste  heat  in  warming  the  room  above.  The  Latrobe 
heater,  so  well  known  in  Baltimore  and  vicinity,  is  another  means  of 
doing  the  same  thing. 

The  mode  of  action  of  a  close  stove  has  been  clearly  and  well 
described  by  Mr.  Briggs:  "Surrounding  any  stove  in  active  operation, 
there  exists  an  envelope  of  air  gradually  ascending,  as  it  acquires  heat, 
toward  the  ceiling.  In  what  way  does  this  envelope  come  to  have  any 
considerable  thickness?  Air  is  nearly  a  perfect  non-conductor  of  heat ; 
one  particle  of  air  does  not,  or  at  least  very  slowly  receives  heat  from 
another  particle.  As  before  stated,  air  permits  the  transmission  of 
radiant  heat  without  absorbing  it.  Only  the  thinnest  film  of  air  can 
possibly  be  in  contact  with  the  surface  of  the  stove  at  any  instant  of 
time,  and  yet  it  is  only  by  contact  that  the  air  is  heated. 

"  In  fact,  the  air  does  not,  nor  does  any  fluid,  whether  gaseous  or 
liquid,  slide  upon  a  surface  along  which  it  passes.  The  movement  is  a 
rolling  one.  D'Arcey  describes  the  movement  of  water  in  a  pipe  to  be 
similar  (but  reversed)  to  the  stripping  of  a  glove  from  the  finger,  by 
turning  the  glove  finger  inside  out. 

"In  a  similar  rolling  movement  the  sheet  of  air  passing  the  stove 
comes  to  have  a  definite  thickness,  and  involves  in  its  rolling  process 
particles  of  air  remote  from  the  ascending  stream. 

"  As  a  stone  thrown  into  a  pool  transmits  its  vibrations  over  the 
surface,  so  any  disturbance  of  a  fluid  body  confined  in  an  inclosure  is 
transmitted  and  communicated  throughout  the  fluid  to  its  most  distant 
part,  with  some  relative  intensity.  There  rises  from  the  stove  a  cur- 
rent of  air  of  considerable  volume,  acquiring,  as  it  ascends,  a  nearly 
uniform  temperature,  but  with  a  nucleus  hotter  than  the  general  tem- 
perature of  the  room.  This  heated  air  endeavors  to  find  its  level  next  the 
ceiling,  but  to  do  so  it  must  not  be  assumed  to  slide  in  under  the  warm 
air  which  it  finds  in  contact  with  the  ceiling.  Instead  of  this,  the  inter- 
position will  be  accomplished  by  a  rolling  action  similar  to  that  on  the 


STOVES.  473 

stove  surface,  wherein  one  set  of  particles  rolls  off  and  the  other  rolls 
upon  the  ceiling  with  mutual  admixture  and  equalization  of  tempera- 
ture in  the  process. 

"  With  the  accumulating  of  a  stratum  of  heated  air  next  the  ceil- 
ing, a  corresponding  absorption  from  the  floor  stratum  must  have 
occurred.  The  necessity  for  the  stove  at  all  is  the  presumption  that 
some  loss  of  heat  must  have  been  going  on  at  the  windows  and  walls 
equivalent  to  the  heat  imparted  by  the  stove. 

"  The  windows  and  walls  impart  *  cold  '  in  the  same  way  and  after 
the  same  laws  of  convection  as  the  stove  imparts  heat.  In  one  part 
of  the  room  the  stove  will  have  been  forming  an  ascendiug  current 
of  considerable  intensity  or  velocity  all  around  itself,  while  at  an- 
other part  the  windows  and  cool  walls  will  have  a  sheet  of  cool  air, 
of  less  velocity,  but  of  equal  heat-value,  traversing  them  downward. 

"  The  most  uniform  distribution  will  be  effected  when  these  cur- 
rents become  the  most  general,  extensive,  and,  consequently,  most  mod- 
erate. Suppose  the  stove  to  have  its  position  remote  from  the  windows 
and  cooling  walls,  and  to  be  so  placed  that  the  average  extent  of  window 
or  wall  surface  or  exposure  shall  be  equidistant  from  the  stove;  it  can 
then  be  asserted  that  the  column  of  hot  air  from  the  stove  will,  after 
rising,  roll  upon  the  ceiling  and  become  intimately  mixed  arid  equalized 
in  temperature  with  the  air  it  finds  there,  and  that  the  sheet  of  descend- 
ing air  from  the  windows  and  walls  will  roll  out  upon  the  floor  and 
intermix  with  the  air  on  that  level,  establishing  an  equality  of  tem- 
perature in  that  stratum.  Within  certain  well-known  limits  of  size  or 
shape  of  room,  and  with  a  close  room,  the  lower  6,  or  8,  or  10 
feet  of  height  of  the  room  wi41  be  heated  by  a  stove  in  any  weather,  so 
that  the  differences  of  temperature  within  that  height  shall  not  affect 
the  comfort  of  the  occupant. 

"  Where  the  stove  employed  is  so  small  as  to  demand  inordinate 
heating  of  its  surface  to  impart  the  required  quantity  of  heat,  success- 
ful warming  is  secured  by  protecting  the  occupants  from  direct 
radiation  by  screens  of  inclosing  envelopes,  which  are  found  to 
accelerate  the  rising  current  of  hot  air,  and  this  is  done  without 
very  materially  impairing  the  distribution  of  heat,  and  even  when  the 
sashes  are  not  very  tight  in  the  window  frames,  tolerable  uniformity 
of  ground  temperature  is  reached."  * 

About  one-third  of  the  effect  is  due  to  radiant  heat  and  the  rest 
to  heat  carried  by  the  air  which  rolls  up  the  heated  sides  of  the  stove 
and  pipe.  In  the  best  forms  of  base-burner,  with  thin  castings  and 
*  The  Sanitary  Engineer ',  September  i,  1880,  page  372. 


474 


STOVES. 


relatively  large  surfaces  of  mica  near  the  glowing  coals,  the  proportion 
of  radiant  heat  is  greater  than  this,  amounting  to  over  one-half  the 
total  effect. 

To  arrange  an  ordinary  cylinder  or  box  stove  so  that  it  shall 
warm  the  fresh  air  entering  the  room,  the  essential  thing  is  to  surround 
it  with  a  jacket  of  sheet  iron  or  zinc,  leaving  the  necessary  opening 
for  access  to  the  stove,  and  then  to  connect  through  an  opening  in  the 
floor  the  space  between  the  jacket  and  the  stove  with  the  outer  air. 
The  amount  of  air  which  will  be  thus  introduced  will  depend  not  only 


FIG.  206. 

on  the  area  of  the  opening  and  the  difference  between  the  temperature 
of  the  room  and  that  of  the  open  air,  but  also  on  the  arrangement 
made  to  secure  exit  of  air  from  the  room.  If  the  room  have  a  fire- 
place in  it  and  the  stovepipe  enters  the  upper  part  of  the  flue  com- 
ing from  this  fireplace,  which  is  a  very  common  arrangement,  the 
exit  of  air  can  be  readily  provided  for  by  leaving  the  fireplace  open. 

If  there  be  no  fireplace,  an  exit  shaft  may  be  carried   up  by  the 
side  of  the  chimney,  from  near  the  floor  to  near  the  ceiling  where  it 


STOVES. 


475 


enters  the  flue,  and  if  this  exit  shaft  be  so  arranged  as  to  receive  heat 
from  the  upper  part  of  the  stovepipe  it  will  work  very  well.     * 


FIG.  207. 


Some  simple  methods  of  using  the  common  stove  for  ventilating 
rooms  are  described  by  Dr.  D.  F.  Lincoln  in   his  paper  on   "  School 


0 


FIG,  208. 


Hygiene,"   printed    in    the   Second   Annual   Report  of  the  Board   of 
Health  of  the  State  of  New  York  for  1881-1882. 


STOVES. 


"In  a  variety  of  ways,"  Dr.  Lincoln  says,  '-the  stove  or  stovepipe 
can  be  used  to  expel  air  from  the  room.  The  'jacket '  or  metal  screen 
is  a  thing  of  which  no  stove  in  an  inhabited  room  should  be  destitute, 
as  a  protection  from  heat.  But  it  is  mentioned  here  as  affording  an 
aid  to  ventilation.  Figure  206  shows  how  this  is  done.  A  metal  cylin- 
der, considerably  wider  than  the  stove,  is  placed  around  the  latter,  and 
its  edge  is  fastened  to  the  floor.  A  good  sized  pipe  is  then  carried 
through  the  floor,  under  the  stove,  and  led  through  the  house  wall  at 
A,  Fig.  206.  Guard  the  inlet  with  a  screen  of  wire  at  A,  and  a  large 
supply  of  pure  warmed  air  is  drawn  into  the  room.  This  is  one  of  the 


FIG.  209. 

cheapest  and  best  devices  for  warming  and  ventilating.  Some  prefer 
to  extend  the  jacket  around  only  a  part  of  the  stove  and  leave  the  door 
uncovered  ;  or  the  jacket  may  stop  at  the  bottom  of  the  stove  and  be 
made  fast  to  the  latter  at  that  point.  The  arrangement  is  equivalent 
to  a  '  portable  furnace/  such  as  is  usually  placed  in  a  cellar  or  a 
basement  hall. 

"  In  Fig.  207  a  stove  is  represented  standing  close  to  an  open 
window.  The  movable  semi-cylinder  of  metal,  commonly  used  for  a 
screen,  has  been  so  placed  as  to  inclose  the  stove  on  all  sides,  except 
that  toward  the  windows.  Cold  air  may  then  be  freely  admitted;  it  is 


STOVES.  477 

quickly  warmed  by  contact  with  the  stove  and  is  thrown  upward,  with 
the  general  current. 

"  Figure  208  shows  air  brought  in  so  as  to  be  warmed  by  contact 
with  a  stovepipe.  The  inlet  flue  is  enlarged  and  runs  up  with  the 
stovepipe  like  a  jacket  for  same  distance. 

"  Figure  209  shows  how  a  stovepipe  may  assist  in  removing  in- 
jurious air.  The  diagram  represents  a  two-story  house  with  a  chimney 
which  comes  down  to  only  a  very  short  distance  from  the  roof.  The 
opening  into  the  chimney  for  the  stovepipe  is  enlarged  so  as  to  receive 
a  much  larger  pipe,  which  encircles  the  stovepipe  like  a  jacket.  This 
jacket  may  stop  short  at  A,  or  may  be  carried  through  the  floor  to  B, 
in  the  first  story.  It  will  secure  a  draught  from  either  story  as  may  be 
arranged.  The  idea  of  this  and  the  preceding  figure  is  borrowed  from 
an  article  in  the  report  of  the  Michigan  Board  of  Health  for  1879." 

I  do  not  propose,  however,  to  describe  the  thousand-and-one 
contrivances  which  may  be  used  to  secure  the  entrance  and  exit  of  air 
in  such  houses  as  those  now  under  consideration.  Each  house  is,  to  a 
certain  extent,  a  problem  by  itself,  but  it  is  a  very  simple  problem, 
which  any  moderately  ingenious  tinner  or  sheet-iron  worker  will  have 
no  difficulty  in  solving,  if  he  will  only  master  the  few  simple  laws  of 
the  movement  of  air,  which  have  been  given  in  previous  chapters. 

Every  stove-dealer  should  possess  this  knowledge  in  order  to  deal 
understandingly  with  the  complaints  which  will  be  made  to  him  about 
bad  draught,  etc.,  etc.,  complaints  which  are  almost  always  due,  rot  to 
the  stove,  but  to  improper  construction  or  location  of  flues. 


CHAPTER  XX. 

VENTILATION  OF  TUNNELS.       RAILWAY  CARS.       SHIPS.      PRISONS.      SHOPS. 
STABLES.       SEWERS.       COOLING  OF   AIR.       CONCLUSION. 

THE  principles  involved  in  the  ventilation  of  tunnels  while  in  pro- 
cess of  construction  do  not  differ  materially  from  those  involved 
in  driving  mine  galleries.  Where  drills  worked  by  compressed  air  are 
used,  as  is  now  commonly  the  case,  the  escaping  air  produces  a  fair 
condition  of  the  atmosphere  at  the  face  of  the  headings  while  the 
drills  are  actually  at  work,  but  additional  means  of  mechanical  ventila- 
tion are  necessary  in  long  tunnels  to  get  rid  otathe  smoke  and  gases 
produced  by  explosions,  and  to  enable  the  rjpsons  and  others  em- 
ployed in  the  shaft  to  obtain  the  requisite  ampunt  of  fresh  air. 

In  the  construction  of  the  Mont  Ceflis  and  the  St.  Gothard 
tunnels  an  aspirating  apparatus,  having  a  capacity  of  about  25,000 
cubic  feet  per  minute  was  employed,  but  it  did  not  succeed  in  ven- 
tilating the  center  of  the  tunnels,  and  there  was  much  sickness  among 
the  workmen,  especially  among  those  employed  in  the  St.  Gothard 
tunnel. 

In  the  construction  of  the  new  Croton  Aqueduct  tunnel  blowers 
were  employed,  from  which  the  air  was  taken  in  spiral  riveted  sheet- 
iron  pipes  to  a  point  about  300  feet  back  of  the  heading.  It  is  best  to 
arrange  such  a  system  so  that  the  action  of  the  blower  can  be  reversed 
so  as  to  exhaust  for  a  short  time  after  blasting,  and  thus  to  remove  a 
large  part  of  the  smoke  and  gases  before  they  diffuse  into  the  tunnel. 
The  pipes  should  be  at  least  12  inches  in  diameter.  If  aspiration  is 
to  be  employed  for  ventilating  the  tunnel  itself  it  is  necessary  that  a 
fresh-air  supply  be  provided,  either  through  a  separate  inlet  or  by 
dividing  the  passage  by  a  partition  or  brattice. 

Attempts  to  produce  currents  by  means  of  compressed  air  jets 
gave  very  poor  results  in  the  Croton  tunnel. 

The  ventilation  of  railway  tunnels  after  they  have  been  con- 
structed presents  special  difficulties  which  depend  mainly  on  the 
frequency  of  the  passage  of  trains  through  them.  In  the  long  tunnels  of 


TUNNEL    VENTILATION.  479 

the  St.  Gothard  and  the  Mont  Cenis  the  passage  of  trains  is  compara- 
tively infrequent,  and  the  difference  in  temperature  between  the 
interior  of  the  tunnel  and  the  outer  air  combined  with  the  piston-like 
action  of  the  train  itself  has  been  found  sufficient  to  produce  the 
necessary  change  of  air.  In  Engineering,  April  21,  1871,  page  286, 
Mr.  Ramsbottom  describes  the  mechanical  ventilation  of  the  Liverpool 
tunnel  on  the  London  and  Northwestern  Railway.  This  tunnel  is 
over  a  mile  in  length,  and  has  a  mean  sectional  area  of  430  square 
feet.  The  ventilation  is  effected  by  a  fan  29  feet  4  inches  in  external 
diameter,  and  7  feet  6  inches  wide,  which  is  placed  in  a  shaft  175  feet 
high  and  23  feet  in  diameter  at  the  top,  rising  from  near  the  center  of 
the  tunnel.  With  a  speed  of  45  revolutions  per  minute  the  fan  cleared 
the  tunnel  of  smoke  and  steam  in  about  eight  minutes,  discharging 
about  431,000  cubic  feet  of  air  per  minute. 

In  a  valuable  paper  on  tunnel  ventilation,  read  before  the 
American  Society  of  Civil  Engineers  in  December,  1890,  Mr.  N.  W. 
Eayrs  describes  the  ventilation  of  the  Hoosac  tunnel  and  the  St.  Louis 
tunnel.  The  Hoosac  tunnel  is  about  4^  miles  long,  perfectly  straight, 
and  is  ventilated  by  an  elliptical  central  shaft  27x15  feet  in  diameter 
and  1,000  feet  high  above  the  top  of  the  tunnel,  which  is  24  feet  wide 
and  22  feet  high.  The  velocity  of  the  air  is  sufficient  to  clear  it  of 
smoke  in  about  15  minutes  after  the  passage  of  a  train.  In  winter  the 
direction  of  the  current  is  from  the  portals  to  and  up  the  central  shaft; 
in  summer  it  is  the  reverse. 

The  St.  Louis  tunnel  is  4,095  feet  long,  and  is  ventilated  by  a  fan 
15  feet  in  diameter  and  9  feet  wide  placed  near  the  center  of  the 
tunnel.  At  no  revolutions  per  minute  the  tunnel  is  cleared  of  smoke 
in  from  four  to  five  minutes.  The  results  have  been  fairly  satisfactory, 
but  Mr.  Eayrs  predicts  that  more  efficient  means  of  ventilation  must 
be  provided  as  traffic  increases,  and  refers  to  the  Mersey  tunnel  at 
Liverpool  as  being  the  best  example  of  successful  ventilation  with 
heavy  traffic.  This  tunnel  is  4,960  feet  long,  under  the  river,  and  is 
26  feet  wide;  it  is  double-tracked  throughout.  The  grade  in  a  portion 
of  the  tunnel  is  196  feet  to  the  mile.  The  principle  on  which  the 
ventilation  was  planned  was  to  admit  fresh  air  at  the  stations,  and 
draw  it  either  way  to  points  midway  between  stations,  where  the  ven- 
tilating fans  were  placed.  An  auxiliary  tunnel  or  air  drift,  7  feet  2 
inches  in  diameter,  runs  parallel  with  the  main  tunnel,  and  is  con- 
nected with  it  and  the  stations  by  sliding  doors,  so  that  air  can  be 
drawn  from  any  point  desired.  The  fans  are  four  in  number,  two  40 
feet  diameter  and  12  feet  wide,  and  two  30  feet  diameter  and  10  feet 


480  TUNNEL    VENTILATION. 

wide.     Their  collective  capacity  is  500,000   feet  per  minute;  average 
number  of  revolutions  per  minute  is  45. 

For  purposes  of  ventilation  the  tunnel  is  divided  into  four  sections, 
one  fan  being  allotted  to  each;  but  by  means  of  the  doors  in  the  air 
passages  the  fans  can  be  made  to  do  each  other's  work,  and  no  com- 
plete stoppage  of  ventilation  is  possible.  The  3o-foot  fan  at  Liver- 
pool ventilates  the  James  Street  station  and  the  section  of  the  tunnel 
between  that  station  and  the  terminus.  The  capacity  of  this  fan  is 
about  T 20,000  cubic  feet  per  minute.  The  4o-foot  fan  at  Liverpool 
ventilates  the  section  of  the  tunnel  between  James  Street  station  and 
the  center  of  the  river.  Capacity  about  130,000  cubic  feet  per  minute. 
The  4o-foot  fan  at  Shore  Road,  Birkenhead,  ventilates  the  section 
between  the  middle  of  the  river  and  the  Hamilton  Square  station,  and 
has  a  capacity  of  130,000  cubic  feet  per  minute.  The  30-foot  fan,  the 
fourth  in  the  series,  is  located  at  Hamilton  Street,  nearly  midway 
between  Hamilton  Square  station  and  Borough  Road,  and  has  a 
capacity  of  about  120,000  cubic  feet.  The  combined  fans  have  a 
capacity  about  one-seventh  that  of  the  entire  tunnel.  These  fans  are 
all  built  on  the  lines  of  the  well-known  Guibal  fan.  About  300  trains 
a  day  pass  through  the  tunnel,  giving  a  maximum  train  service  of  one 
train  each  way  every  five  mintrtes.  With  this  heavy  traffic,  and  with  the 
severe  grades,  the  ventilation  of  both  tunnel  and  stations  is  excellent. 

Several  schemes  have  been  proposed  for  getting  rid  of  the 
offensive  fumes  and  gases  thrown  off  by  coal-burning  locomotives  in 
passing  through  such  tunnels  as  those  of  the  underground  railway  in 
London,  the  Fourth  Avenue  tunnel  in  New  York,  the  Baltimore  tunnels, 
etc.  One  is  that  of  Dr.  Richard  Neale  to  absorb  the  sulphur  fumes 
and  carbonic  acid  by  means  of  trays  of  lime  or  screens  kept  wet  with 
alkaline  solutions,  forming  what  he  calls  a  chemical  lung.  Another  is 
to  cut  off  the  upper  part  of  the  tunnel  by  a  horizontal  partition  having 
a  slit  in  it  for  the  passage  of  the  top  of  the  locomotive  smoke-stack, 
and  to  discharge  all  the  smoke,  etc.,  into  this  upper  flue,  from  which 
it  is  to  be  drawn  by  an  exhaust  fan.  This  has  been  patented.  Another 
plan  is  that  of  Mr.  Anderson,  in  which  a  cast-iron  duct  with  valves  16 
feet  apart  is  laid  between  the  rails  and  receives  the  smoke  and  gases 
from  the  locomotive.  The  valves  are  opened  by  a  slide  suspended 
from  the  locomotive  in  such  a  way  that  before  one  valve  closes  a 
second  one  is  opened.  The  true  solution  will  probably  be  the  use  of 
motors  which  do  not  produce  smoke  and  gases. 

In  a  series  of  determinations  of  the  proportion  of  carbonic  acid 
in  the  air  of  passenger  and  smoking  cars  made  by  Prof.  William  R. 


RAILWAY    CARS.  481 

Nichols,  and  published  in  the  Sixth  Report  of  the  Massachusetts  State 
Board  of  Health,  1875,  the  amount  was  found  to  be  from  14  to  36  parts 
per  10,000.  Probably  the  worst  air  ever  tested  was  that  in  an  American 
railway  car  running  between  St.  Petersburgh  and  Moscow  in  the  winter 
of  1866.  This  car  was  50  feet  long  and  carried  80  third-class  passengers, 
the  outside  temperature  was  22°  F.  below  zero  and  the  only  means  of 
heating  the  car  were  the  bodies  of  the  inmates.  In  nine  hours  the  tem- 
perature in  the  upper  part  of  the  car  was  21°  F.  and  at  the  floor  was 
6°  F.  below  zero,  while  the  carbonic  acid  had  iucreased  from  14  per 
10,000  at  starting  to  94  per  10,000. 

Another  series  of  carbonic  acid  tests  made  by  Professor  Howard 
is  given  in  the  Report  on  the  Sanitary  Inspection  of  Passenger  Coaches 
by  Dr.  R.  Harvey  Reed,  published  in  1888,  the  figures  ranging  from 
4.4  per  10,000  in  July,  when  all  doors  and  windows  were  probably 
open,  to  14.26  per  10,000  in  December.  All  the  figures  in  this  series 
are  low — so  low  in  fact  as  to  make  it  probable  that  some  source  of  error 
existed  in  the  analyses. 

Many  inventors  have  busied  themselves  with  the  problem  of  venti- 
lating railway  cars,  and  many  patents  have  been  granted  for  appliances 
for  this  purpose,  but  thus  far  the  difficulties  have  not  been  overcome. 
The  problem  is  to  provide  an  apparatus  which  will  change  the  air  in  a 
passenger  coach  at  least  once  in  five  minutes,  which  will  do  this  while 
the  car  is  standing  still  as  well  as  while  it  is  in  motion,  and  which  will 
exclude  dust.  This  cannot  be  done  if  the  windows  of  the  car  are 
under  the  control  of  the  passengers,  and  it  cannot  be  done  by  any 
openings  into  the  car,  whether  at  top,  bottom  or  sides,  without  the  ap- 
plication of  mechanical  power.  A  combination  of  fans  run  by  electro- 
motors, with  steam  pipes  passing  in  metal-lined  ducts  placed  at  the 
angle  formed  by  the  sides  and  floor  of  the  cars,  the  fresh  air  to  enter 
around  these  pipes  through  dust-filtering  screens,  and  the  fans  to  draw 
off  air  from  above,  would  seem  to  be  indicated  in  this  case.  The  sup- 
ply of  air  should  be  not  less  than  900  cubic  feet  of  air  per  head  per  hour, 
and  the  ducts,  fans,  etc.,  should  be  of  such  size  that  in  warm  weather 
this  amount  could  easily  be  doubled  without  opening  doors  or  win- 
dows. 

SHIPS. 

Some  of  the  earlier  attempts  to  improve  upon  the  old-fashioned, 
and  still  usual,  method  of  ventilating  ships  by  means  of  windsails  are 
referred  to  in  Chapter  II.  of  this  work.  Since  the  time  of  Sutton, 
about  100  patents  have  been  granted  for  methods  of  ship  ventilation, 
but  none  of  these  have  met  with  general  acceptance,  and  for  sailing 


482  SHIP    VENTILATION. 

vessels  and  freight  steamers  the  windsail  is  still  almost  the  only  appli- 
ance used.  In  modern  ships  of  war  and  in  large  passenger  steamers 
of  recent  construction  fans  are  used  and  give  good  results,  but  they 
are  always  supplemented  by  large  cylindrical  vertical  pipes  projecting 
above  the  deck,  with  movable  cowls  having  trumpet-shaped  mouths, 
which  can  be  turned  so  as  to  either  face  the  wind  or  away  from  it.  In 
a  few  ships  a  form  of  air  pump  has  been  tried  which  is  worked  by  the 
rolling  of  the  vessel,  but  the  effect  is  small,  being  less  than  2,500  cubic 
feet  of  air  per  hour.  On  the  berth  deck  of  a  warship  constructed  20 
years  ago  each  man  will  have  less  than  120  cubic  feet  of  air  space,  one 
watch  being  on  deck,  and  with  all  openings  in  port  the  proportion  of 
carbonic  acid  may  rise  to  from  15  to  34  parts  in  10,000.  Upon  the 
best-arranged  and  best-ventilated  of  the  new  passenger  steamships  on 
the  New  York  and  Liverpool  lines,  which  have  fan  ventilation  and 
many  wind  tubes,  the  air  in  the  staterooms  of  the  first-cabin  passengers 
is  usually  nearly  free  from  odor,  the  proportion  of  carbonic  acid  present 
being  probably  about  8  per  10,000. 

The  idea  of  obtaining  motive  power  for  the  air  by  the  use  of  the 
galley  or  furnace  fires  of  the  ship,  as  was  proposed  by  Sutton,  has 
been  often  tried  but  with  only  partial  success,  chiefly  because  the 
pipes  used  were  entirely  too  small.  But  on  the  fast  North  Atlantic 
steamers  the  furnace  fires  cannot  be  used  to  aspire  air  to  feed  them 
from  remote  parts  of  the  ship,  because  they  must  have  the  largest  pos- 
sible supply  of  air,  free  from  friction  to  enable  them  to  do  their  work, 
and  hence  are  put  in  almost  direct  connection  with  the  outer  air  by 
large  hatchways. 

On  some  of  our  most  recently-constructed  steel  cruisers  the  fresh- 
air  supply  is  ordinarily  obtained  through  hatchways  and  ventilating 
tubes  with  movable  cowls  and  the  foul  air  is  drawn  out  through  special 
ducts  connected  with  Sturtevant  blowers.  On  the  cruiser  "  Baltimore  " 
the  cubic  air  space  per  man  on  the  forward  berth  deck  is  142.3 
cubic  feet  for  247  men.  There  are  two  exhaust  blowers,  each  5  feet 
6  inches  in  diameter,  with  a  capacity  of  10,000  cubic  feet  per  minute 
and  connected  with  a  main  air  duct  23  inches  in  diameter.  From  this 
main  duct  smaller  ducts  pass  to  nearly  all  parts  of  the  ship  except  the 
boiler  space.  From  the  berth  deck  above  referred  to  there  are  14  of 
these  exhaust  ducts,  each  4  inches  in  diameter  and  opening  near  the 
ceiling.  '  There  is  no  heating  apparatus  for  this  deck.  On  the  cruiser 
"San  Francisco"  the  plan  is  essentially  the  same;  the  berth  deck  gives 
12 1. 2  cubic  feet  of  air  space  to  each  of  302  men,  the  blowers  are  5  feet 
in  diameter  and  the  main  air  duct  is  27x15  inches. 


SHIP    VENTILATION.  483 

On  the  gunboat  "Yorktown,"  the  berth  deck  gives  76  cubic  feet 
of  air  space  to  each  of  87  men,  and  the  two  exhaust  blowers  discharge 
into  the  fireroom,  the  main  ducts  being  14  inches  in  diameter.  In  all 
these  ships  the  fans  can  be  reversed  so  as  to  blow  air  in  instead  of 
drawing  it  out,  it  being  the  intention  to  use  this  method  in  very  rough 
weather,  or  for  the  purpose  of  driving  sulphurous  acid  fumes  through 
the  ship  for  purposes  of  disinfection  if  required.  For  the  above  data 
I  am  indebted  to  the  courtesy  of  Capt.  T.  D.  Wilson,  Chief  of  the 
Bureau  of  Construction  of  the  Navy. 

Medical  Inspector  W.  K.  Van  Reypen,  U.  S.  Navy,  informs  me  that 
on  the  '*  San  Francisco,"  when  the  blowers  are  running  at  400  revolu- 
tions, the  berth  deck,  storerooms,  sick  bay  and  officers'  quarters  are 
well  ventilated,  but  that  the  engine  and  firerooms  are  excessively  hot, 
and  are  only  ventilated  by  funnels  and  windsails.  The  compartment 
for  the  dynamo  and  steam-steering  apparatus  is  almost  uninhabitable 
on  account  of  the  heat,  and  Dr.  Van  Reypen  recommends  that  a 
separate  blower  be  provided  of  sufficient  capacity  and  power  to 
thoroughly  ventilate  the  engine-room,  fireroom  and  dynamo  com- 
partment. 

As  regards  the  "Yorktown,"  Surgeon  George  E.  H.  Harmon, 
U.  S.  Navy,  states  that  the  ventilation  of  the  forward  part  of  the  ship 
is  fairly  well  effected,  but  that  that  of  the  after  part  is  not  satisfactory. 
The  delivery  of  the  foul  air  into  the  firerooms  interferes  with  the 
downward  cool  air  current  through  the  cowled  ventilators  from  the 
open  air  above,  and  thus  raises  the  temperature  and  adds  materially 
to  the  suffering  of  the  firemen. 

The  pipes  leading  from  the  wardroom  and  officers'  rooms  in  the 
after  part  of  the  ship  open  into  a  large  space  between  decks.  One 
of  these  decks  is  not  air  tight  and  has  several  hatches,  the  result  being 
that  the  aspiration  from  the  officers'  quarters  is  very  small.  In  this 
ship  the  dynamo  room  is  ventilated  by  a  special  blower,  and  the  result 
is  good. 

In  warships  of  the  monitor  type  constant  mechanical  ventilation 
is  of  course  a  necessity.  On  the  "  Miantonomoh  "  the  principal  berth 
deck  may  be  fairly  ventilated  at  all  times,  but  the  turret  chambers, 
which  are  occupied  by  hammocks  at  night,  have  no  provisions  for 
change  of  air.  The  indraught  registers  on  the  berth  deck  are  flush 
with  the  deck  and  admit  an  undue  amount  of  dust  from  the  sweepings, 
etc.,  into  the  flues,  the  interior  of  which  is  practically  inaccessible. 

A  simple  and  compact  arrangement  of  a  blowing  fan  combined 
with  radiators  and  automatic  regulation  of  temperature  has  been 


484  SHIP    VENTILATION. 

placed  on  some  of  the  New  York  ferryboats  on  the  East  River  and 
produces  very  good  results.  Heating  is  in  this  case  more  important 
than  ventilation. 

The  British  steamship  "Ophir,"  of  the  Oriental  line  to  Australia, 
is  ventilated  by  means  of  jets  of  compressed  air  which  are  used  to 
induce  movement  of  the  air  surrounding  the  jets.  This  does  not 
appear  to  be  an  economical  way  of  applying  power  to  effect  the 
movement  of  air,  but  it  has  the  advantage  in  hot  climates  of  cooling 
it  somewhat  if  water  is  used  to  convey  away  the  heat  generated  in 
the  compression  chambers. 

The  rules  for  the  ventilation  of  transports  issued  by  the  Sanitary 
Commission  of  Bombay  in  1866  direct  that  the  space  between  decks 
occupied  by  troops  shall  be  kept  free  of  partitions,  and  that  an  air- 
shaft  at  least  2^  feet  square  shall  be  placed  at  each  end  of  this  space, 
having  its  lower  end  flush  with  the  ceiling.  Four  metal  tubes,  each  18 
inches  in  diameter,  with  movable  cowls  to  face  the  wind  are  to  be 
inserted,  two  on  each  side,  one  about  one-fourth  of  the  length  of  the 
deck  from  the  foremost  end,  the  other  the  same  distance  from  the 
after  end.  At  9  inches  below  the  bottom  of  each  tube  is  to  be  fixed  a 
horizontal  screen  to  deflect  the  air  along  the  ceiling.  Apparently  this 
is  to  provide  for  the  needs  of  four  or  five  hundred  men,  and  it  might 
give  each  man  15  cubic  feet  of  air  per  minute  with  a  good  wind. 

The  most  complete  published  report  upon  the  ventilation  of  a 
modern  warship  that  I  have  seen  is  that  by  J.  Gartner  upon  the  iron 
corvette  "Sachsen"  in  the  Deutsche  Vierteljahrsschrift  f.  offend. 
Gsndhtspflege,  Vol.  13,  1881,  page  369.  This  gives  data  as  to  the 
temperature,  moisture  and  carbonic  impurity  of  the  air  at  different 
points,  the  direction  of  currents,  etc.  Mechanical  ventilation  for  cer- 
tain parts  of  the  ship  was  provided  by  blowers,  and  when  these  were 
acting  the  carbonic  impurity  was  from  10  to  20  per  10,000.  In 
some  parts  of  the  ship  the  amount  of  carbonic  acid  was  so  great 
that  lamps  burned  dimly  and  respiration  was  affected.  In  a  general 
way  it  may  be  said  that  the  air  was  as  impure  as  it  is  in  a  crowded 
theater,  yet  there  was  comparatively  little  sickness.  Under  some 
circumstances  the  ventilation  of  the  hold  of  a  ship  should  be  re- 
stricted to  fine  weather  in  order  to  prevent  the  damage  to  certain 
articles  of  cargo  which  may  be  produced  by  admitting  to  them  air 
loaded  with  moisture. 

PRISONS. 

If  the  objects  in  view  in  the  construction  of  a  prison  are  merely 
the  safe  keeping  of  the  prisoners  and  the  prevention  of  palpable  and 


PRISON    VENTILATION.  485 

evident  filth,  without  attempting  to  furnish  better  ventilation  or  more 
healthful  surroundings  than  are  to  be  found  in  the  bedroom  of  the 
average  laborer  or  than  they  are  accustomed  to  in  the  dens  and  slums 
from  which  most  of  them  come,  if,  in  other  words,  it  is  intended  that 
no  special  effort  shall  be  made  to  preserve  and  improve  the  health  of 
the  convicts,  but  that  they  shall  be  left  to  the  natural  processes  of  ex- 
termination of  the  unfittest,  then  the  majority  of  o.ur  prisons  will  meet 
these  requirements  so  far  as  ventilation  is  concerned. 

Municipal  station  houses  and  jails  intended  for  the  temporary 
detention  of  prisoners  are  usually  heated  by  direct  radiation  and  have 
little  or  no  provision  for  fresh-air  supply  in  cold  weather.  In  the 
larger  penitentiaries,  for  long-time  detention  of  convicts,  there  are 
usually  a  few  fresh-air  openings,  quite  insufficient  to  secure  the  desired 
amount,  and  some  of  the  cells  are  much  more  heated  than  others.* 
The  defective  ventilation  in  penitentiaries  is  one  reason  why  the  deathl 
rate  from  consumption  is  so  great  in  them,  another  reason  being  that"* 
the  criminal  class  is  especially  liable  to  this 'disease,  so  that  the  pro- 
portion of  persons  who  are  affected  with  tuberculosis  when  they  enter 
prison  is  about  twice  as  great  as  is  found  in  other  people  of  the  same  age. 

There  are  wide  differences  of  opinion  among  wardens  and  other 
officials  of  prisons  as  to  how  such  buildings  should  be  constructed, 
whether  the  cells  should  have  brick,  stone  or  iron  walls,  how  many 
tiers  of  cells  are  best,  whether  central  or  lateral  corridors  are  to  be 
preferred,  and  whether  solitary  confinement  should  be  the  rule  or  the 
exception,  but  all  of  them,  or  nearly  all,  declare  that  one  of  the  chief 
objects  of  the  penitentiary  is  the  reformation  of  the  prisoner,  and  that 
this  cannot  be  accomplished  unless  he  is  kept  in  good  health  and  is 
given  plenty  of  fresh  air. 

If  this  is  to  be  done  each  man  should  receive  at  least  2,500  cubic 
feet  of  fresh  air  per  hour.  The  openings  for  exit  and  entrance  of  air 
should  be  beyond  the  control  of  the  prisoner,  and  the  temperature 
should  not  vary  more  than  3  degrees  in  different  cells. 

There  are  two  essentially  different  plans  of  prison  construction  in 
use.  In  the  first,  known  as  the  Pentonville  or  the  Auburn  system,  the 
cells  are  arranged  in  blocks  of  several  tiers  in  height,  and  this  block  is 
surrounded  by  an  outer  building,  between  the  walls  of  which  and  the 
doors  of  the  tiers  of  cells  in  each  side  is  an  open  corridor,  not  divided 
by  floors  corresponding  to  the  floors  of  the  several  tiers,  the  area  of 
this  hall  being  unobstructed  from  the  floor  of  the  first  story  to  ceiling 
of  upper  story,  as  shown  in  Fig.  210,  which  is  a  cross-section  of  one  of 
the  cell  blocks  in  the  New  York  State  Reformatory  at  Elmira. 


486 


PRISON    VENTILATION. 


The  heaters  are  round,  vertical  tube  radiators  set  under  the  win- 
dows, with  openings  in  the  center  of  the  bases.  In  corresponding 
openings  in  the  stone  flags  are  set  strong  cast-iron  pipes,  with  flanges 
built  into  the  masonry.  These  pipes  extend  ilp  through  the  openings 
in  the  bases  of  the  radiators  which  they  fit  closely,  connecting  the 
fresh-air  ducts  with  the  radiators  and  preventing  water  (when  washing 
the  floors)  from  entering  the  ducts. 

The  number  of  concentric  rows  of  tubes  in  the  radiators  is  four. 
The  two  outer  rows  are  separated  from  the  inner  ones  by  a  galvanized 


FIG.  210. 


sheet-iron  partition,  the  object  being  to  divide  the  inside  rows  from 
the  outer  ones  so  as  to  make  part  of  each  radiator  practically  an  in- 
direct heater,  the  air  from  the  duct  only  coming  in  contact  with  the 
inner  rows,  while  the  outer  rows  warm  the  air  already  within  the  halls 
and  give  direct  radiation. 

There  are  500  cells,  each  of  which  have  two  4X4-inch  flues,  one 
from  near  the  ceiling  and  the  other  from  a  cast-iron  niche  near  the 
floor.  The  one  near  the  ceiling  is  fitted  with  a  heavy  cast-iron,  frame 
built  into  the  walls,  while  the  lower  one  connects  with  the  top  of  the 


PRISON    VENTILATION.  487 

"  night-bucket  "  niche.  The  flues  are  separate  their  whole  length,  each 
terminating  in  the  exhaust  chamber  c  as  shown,  and  there  are  no  means 
of  closing  them. 

The  exhaust  chambers  extend  the  whole  length  of  the  blocks  of 
cells,  so  that  the  flues  are  perfectly  straight,  a  person  in  the  chamber 
being  able  to  see  the  light  in  the  cells. 

The  steam  coils  within  the  exhaust  chambers  are  i*4-inch  pipes 
and  extend  over  the  upper  ends  of  all  the  flues. 

The  air  ducts  extend  all  around  the  wings  near  the  outer  walls 
as  shown,  and  communicate  with  the  fresh-air  shafts  or  towers,  each 
tower  having  a  separate  section  of  duct. 

The  course  of  the  fresh  air  is  in  at  the  window  a  and  down 
through  the  tower,  thence  through  the  air  ducts  to  the  radiators, 
through  which  it  passes  to  the  halls,  from  which  it  is  drawn  into  the 
cells  by  the  action  of  the  independent  flues,  thence  out  through  the 
aspirator. 

The  coils  in  the  aspirator  or  exhaust  chamber  are  not  connected 
with  the  regular  heating  system  of  steam  pipes,  but  with  a  special  sys- 
tem provided  for  them,  with  the  valves  in  the  boiler  room,  so  that 
they  can  be  under  the  control  of  the  engineer  without  his  entering  the 
buildings,  and  also  to  admit  of  using  the  exhaust  chamber  and  coils 
during  the  summer  and  when  steam  is  not  otherwise  required,  which 
is  done,  causing  a  rapid  movement  at  all  seasons.* 

In  a  system  of  this  kind  the  upper  tier  of  cells  must  be  overheated 
if  the  lower  tier  is  to  be  kept  comfortable  in  cold  weather,  and  the 
greater  the  number  of  tiers  the  greater  the  difficulty  in  this  respect. 
On  this  plan  there  should  not  be  more  than  two  tiers  of  cells. 

A  much  better  plan  is  to  separate  each  double  row  of  cells  by  a 
passageway  from  4  to  6  feet  wide,  as  is  done  in  the  Rhode  Island  State 
Prison.  In  this  passageway  can  be  carried  the  heating  and  ven- 
tilating apparatus.  In  the  Rhode  Island  Prison  there  are  three  tiers 
of  cells,  and  the  halls  containing  them  are  heated  by  direct-indirect 
radiation.  Each  cell  has  a  5-inch  foul-air  flue  extending  from  near  its 
floor  to  the  roof  where  it  is  capped  with  a  cowl.  For  reasons  given  on 
page  275  so  many  separate  upcast  flues  are  undesirable,  unless  each 
cell  has  an  independent  air  supply. 

A  modification  of  this  plan   is  that  patented  by  Mr.  Charles  E. 

Felton,  and  used  in  the  House  of  Correction  at  Chicago.     In  this  the 

heating  apparatus  and  fresh-air  flues  are  also  in  the  central   passage, 

and  are  so  arranged  that  each  cell  has  its  own  heating  surface  and 

*  From    The  Sanitary  Engineer,  April  26,  1883. 


488  WORKSHOP    VENTILATION. 

fresh-air  supply  in  the  rear  wall  of  the  cell.  In  a  system  of  this  kind 
it  is  best  that  the  fresh-air  entrance  be  near  the  ceiling  and  the  foul- 
air  outlet  near  the  floor.  To  ensure  constant  movement  of  the  air  all 
the  foul-air  ducts  should  unite  into  one  which  should  be  connected 
with  an  aspirating  chimney  or  with  an  aspirating  fan.  If,  however,  the 
solitary  confinement  plan  is  to  be  really  carried  out,  this  uniting  of 
ducts  may  furnish  a  means  of  communication  between  prisoners  which 
is  not  desirable,  unless  special  arrangements  are  made  to  prevent  this. 

The  other  type  of  prison  construction  is  that  in  which  the  cells 
are  arranged  in  tiers  on  each  side  of  a  central  hall,  the  outer  walls  of 
the  cells  being  formed  by  the  outer  wall  of  the  building.  This  is  the 
plan  of  the  Eastern  Penitentiary  in  Philadelphia,  in  which  the  heating 
of  the  cells'  is  partly  by  the  admission  of  warm  air  from  the  central 
hall,  but  mainly  by  a  single  line  of  steam  pipe  which  passes  around 
the  base  of  the  cell  near  the  floor.  The  result  is  great  variation  in 
temperature  in  the  different  cells,  ranging  from  70°  to  82°  F.  in  one 
block.  Each  cell  has  a  small  opening  from  2  to  4  inches  in  diameter 
near  the  floor  in  the  outer  wall  for  the  admission  of  fresh  air,  but  this 
is  invariably  plugged  up  in  some  way  by  the  prisoner  in  cold  weather. 
The  foul-air  outlet  is  in  the  ceiling,  and  is  also  often  closed.  No 
aspirating  force  is  employed.  The  result  is  that  the  air  in  a  cell  is 
often  very  impure,  the  carbonic  impurity  added  having  been  found  to 
be  from  4  to  9.5  parts  in  10,000,  and  this  has,  no  doubt,  been  one 
cause  of  the  high  death  rate  from  consumption  in  this  prison. 

In  the  Lackawanna  Prison,  described  and  figured  in  The  Engineer- 
ing Record  of  March  2,  1889,  the  cells  are  also  on  each  side  of  a  central 
corridor,  but  the  heating  is  by  indirect  radiation,  the  registers  being 
cast  in  the  sill  of  the  iron  door  frames  of  the  cells.  The  foul-air 
flues  in  the  outer  walls  open  near  the  floor  and  connect  above  with 
ducts  leading  to  an  aspiration  shaft. 

SHOPS,  ETC. 

The  ventilation  of  workshops,  factories,  mills,  etc.,  is,  as  a  rule, 
not  a  difficult  matter,  although  it  is  rarely  attended  to.  Power  is 
usually  available  for  some  form  of  mechanical  ventilation.  An  ex- 
ample of  a  good  system  of  ventilation  by  means  of  an  aspirating 
chimney  is  given  by  L.  Perreau,  who  arranged  it  for  a  weaving  shed 
201x108  feet  and  n  feet  high,  in  which  400  persons  were  employed. 
About  1,500  cubic  feet  of  air  per  head  per  hour  is  supplied  which 
enters  by  128  openings  at  the  roof,  and  the  foul  air  is  drawn  off 
through  openings  in  the  floor  into  ducts  leading  to  the  factory  chimney, 


STABLE    VENTILATION.  489 

which  is  49.4  square  feet  in  sectional  area  and  177  feet  high,  and  the 
temperature  in  which  is  over  400°  F.  when  the  five  steam  boilers  con- 
nected with  it  are  at  work.  The  shed  is  heated  by  overhead  pipes, 
and  the  fresh  air  is  drawn  down  over  these  by  the  aspirating  chimney.* 

In  some  shops,  as  in  paper  mills,  a  great  volume  of  steam  is  pro- 
duced which  should -be  removed  promptly.  For  this  purpose  a  heated 
hood  or  diaphragm  placed  above  the  dryers  has  been  found  to  work 
well,  producing  an  upward  current.  An  exhaust  fan  connected  with 
the  hood  and  forcing  the  steam  through  thin  metal  pipes  of  8  and  10 
inches  diameter,  in  which  it  would  condense,  would  be  an  economical 
method  of  dealing  with  such  vapors,  as  the  heat  evolved  in  condensa- 
tion and  the  hot  water  produced  could  both  be  used  to  warm  the  room. 
In  workshops,  as  in  most  other  rooms,  the  ventilation  problem  is  how 
to  get  enough  fresh  air  in  at  the  proper  points,  for  if  this  be  done  there 
is  little  difficulty  in  disposing  of  the  foul  air. 

It  is  the  neglect  of  this  point  that  often  produces  trouble  in  large 
store  or  warehouses  in  which  at  times  there  are  stored  quantites  of 
substances  liable  to  produce  unpleasant  odors — as,  for  instance,  a  large 
quantity  of  sweating  grain.  Ventilation  will  not  be  produced  by 
merely  making  a  hole  in  the  roof — not  even  if  an  exhaust  fan  is  placed 
in  the  hole.  There  must  be  air  inlets  so  placed  that  the  currents  from 
them  to  the  outlets  will  change  the  air  of  the  room. 

STABLES. 

For  all  temperatures  above  32°  F.  the  amount  of  air  supply  for 
horses,  oxen  and  sheep  should  be  unlimited,  to  obtain  the  best  results. 
Where  it  must  be  limited,  it  should  be,  for  a  horse,  from  4,000  to  6,000 
cubic  feet  of  fresh  air  per  hour. 

In  the  model  plan  of  a  stable  proposed  by  the  English  Barracks 
and  Hospital  Improvement  Commission  in  1863,  100  square  feet  of 
floor  space  and  1,605  cubic  feet  of  air  space  were  allowed  to  each 
horse.  Fresh-air  inlets  giving  i  square  foot  of  area  per  horse  were 
provided  at  the  eaves  by  means  of  air  bricks  or  Sheringham  valves,  and 
to  ensure  a  fresh-air  supply  near  the  head  of  the  horse  when  he  is  lying 
down,  an  air  brick,  low  down,  is  placed  between  every  two  stalls.  The 
outlet  is  by  a  louver  at  the  edge  giving  4  square  feet  outlet  to  each 
horse. 

For  cavalry  stables  in  the  English  climate  this  would,  no  doubt 
answer  well,  but  in  cold  and  windy  weather  the  currents  produced 
through  the  lower  openings  would  at  times  be  dangerous. 

*  See  Compte  Rendu  de  la  Soc.  des  Ingenieurs  Civils,  August,  1890,  293. 


490  STABLE    VENTILATION. 

According  to  Dr.  F.  Smith*,  a  horse  inhales  about  45  cubic  feet 
of  air  per  hour  and  gives  off  between  6  and  7  cubic  feet  of  carbonic 
acid  in  the  same  time.  He  accepts  for  stables  the  same  ratio  of  per- 
missible carbonic  impurity  as  that  fixed  by  Parkes  and  De  Chaumont 
for  barrack  rooms — namely,  2  parts  in  10,000,  and  using  De  Chau- 

mont's  formula  of  £-  =  </,   where  e  =  the  number  of  cubic  feet  of  CO0 

P 
exhaled  per  hour — viz.,  6.5;  p  =  the  limit   of  carbonic   impurity  per 

cubic  foot  of  air  permissible— viz.,  .0002;  and  d—  the  number  of  cubic 
feet  of  fresh  air  per  horse  required,  the  result  is  •  =32  500  cubic 

.0002 

feet  of  air  per  hour.  In  the  last  edition  of  Parkes'  "Hygiene"  (page  187) 
misgiven  as  i.13,  which  would  make  the  air  supply  required  5,650 
cubic  feet  per  hour,  and  this  is  more  nearly  correct.  In  stables  built 
of  brick  and  of  what  is  ordinarily  called  good  construction,  the  ar- 
rangements for  air  supply,  when  they  are  provided  at  all,  usually  are 
for  a  much  smaller  supply  than  this.  No  doubt,  horses  and  cattle  can 
endure  a  smaller  supply  of  fresh  air  in  proportion  to  their  weight  than 
man  without  great  risks  of  producing  disease;  even  so  low  an  allow- 
ance as  500  cubic  feet  per  hour  per  horse  in  a  large  car  stable  has  not 
produced  evident  bad  results,  but  in  this  case  the  stable  afforded  each 
horse  1,200  cubic  feet  of  air  space,  half  the  horses  were  out  the  greater 
part  of  the  time,  and  much  change  of  air  went  on  through  open  doors, 
etc.,  besides  that  specially  provided  for  by  the  ventilating  tubes.  The 
most  extended  series  of  examinations  of  air  of  stables  which  I  have 
met  with  is  contained  in  a  work  by  Prof.  Max  Marker,  a  translation 
of  which,  by  Professor  Leyder,  under  the  title  of  "Recherches  sur  la 
Ventilation  Naturelle  et  la  Ventilation  Artificielle  principalement  dans 
les  etables,"  was  published  in  Paris  in  1873.  Professor  Marker  found 
the  proportion  of  carbonic  acid  in  some  stables  in  which  the  health  of 
the  animals  seemed  good  to  be  from  30  to  40  parts  per  10,000,  or  three 
or  four  times  as  great  as  that  fixed  by  Pettenkofer  as  the  permissible 
limit  of  impurity  for  human  habitations. 

Of  late  years  architects  have  been  called  on  for  plans  of  some 
elaborate  and  costly  stable  buildings  intended  for  fine  horses,  and  in 
these  there  are  required  special  arrangements  for  warming  and  venti- 
lation. Thus  in  Mr.  Work's  stable,  described  in  The  Sanitary  Engi- 
neer of  November  8,  1883,  the  air  supply  for  10  horses  is  furnished 
through  a  direct-indirect  radiator  having  4  square  feet  of  opening, 
and  outlets  into  special  flues  are  provided  near  the  ceiling.  The  ducts 
*  "  Manual  of  Veterinary  Hygiene,"  Lond.,  1887. 


SEWER    VENTILATION.  49! 

are  too  small  for  a  proper  supply  for  10  horses,  and  it  would  have  been 
better  to  have  made  outlets  for  the  foul  air,  both  above  and  near  the 
floor,  into  special  vertical  flues. 

A  better  arrangement  is  that  in  Mr.  Pickhardt's  stable,  described 
and  illustrated  in  The  Sanitary  Engineer  of  July  26,  1883.  In  this 
building  the  fresh  air  is  brought  in  through  indirect  radiators  and 
discharged  into  the  room  through  four  registers,  one  in  each  corner, 
about  8  feet  above  the  floor.  The  outlets  are  about  i  foot  above  the 
floor  and  open  into  flues  i  foot  square  which  extend  6  or  7  feet  above 
the  room  and  have  each  at  least  9  square  feet  of  surface  of  accelerat- 
ing steam  coil. 

In  planning  the  ventilation  of  a  stable  that  is  to  be  well  built, 
and  not  to  rely  on  cracks,  open  doors,  etc.,  for  fresh  air,  flues,  regis- 
ters, etc.,  a  supply  of  6,000  cubic  feet  of  air  per  hour  per  horse  should 
be  provided  for,  and  the  heating  surface  should  be  proportioned 
to  heat  this  amount  of  air  from  zero  to  60°  F.  It  is  easy -to  diminish 
the  air  supply  or  the  heat,  or  both,  to  suit  circumstances,  and  the 
proper  apparatus  will  cost  very  little  more  than  one  adapted  to  half 
the  above  estimate. 

SEWERS    AND    HOUSE    DRAINS. 

All  sewers  and  soil  pipes  should  be  provided  with  the  means  of 
securing  an  abundant  and  nearly  constant  supply  of  fresh  air  in  order 
to  promote  the  growth  of  the  aerobic  micro-organisms,  which  are  the 
chief  agents  in  decomposing  the  organic  matters  contained  in  them, 
and  to  dilute  and  remove  the  offensive  or  noxious  gases  which  may  be 
developed  in  them.  If  the  sewers  are  properly  planned  and  con- 
structed, with  smooth  inverts  of  uniformly  sufficient  downward  grade 
toward  the  outlet,  and  with  a  sufficient  supply  of  water — while  only 
fresh  sewage  is  admitted  to  them — their  ventilation  is  a  comparatively 
easy  matter.  The  tendency  to  the  production  of  foul  gases  in  such 
sewers  is  small;  and  if  openings  to  the  outer  air  are  provided  at  inter- 
vals, care  being  taken  that  such  an  opening  is  placed  at  every  dead  end,  a 
constant  movement  of  air  will  be  secured  through  the  influence  of  winds, 
of  the  differences  in  temperature  and  moisture  between  the  sewer  air 
and  the  free  atmosphere,  and  of  the  movement  of  the  current  of  sewage. 

Under  such  circumstances,  the  precise  direction  of  the  current 
matters  little,  and  it  is  unnecessary  to  provide  shafts  with  cowls  or  fur- 
naces to  induce  a  current  in  a  particular  direction. 

It  has  often  been  proposed  to  ventilate  sewers  by  means  of  large 
tall  shafts  or  chimneys  specially  constructed  for  the  purpose — or 
through  the  chimneys  and  furnaces  of  large  factories — and  the  ex- 


492  AIR    COOLING. 

periment  has  been  tried,  but  the  influence  of  such  shafts  extends  only 
to  the  nearest  inlet;  and  if  this  be  two  or  three  hundred  yards  away, 
the  influence  is  small,  owing  to  the  immense  quantities  of  soil  air 
which  stream  in  through  the  walls  of  ordinary  brick  sewers.  Where 
the  sewers  and  house  drains  are  under  the  control  of  the  municipal 
engineers,  and  are  properly  constructed  and  managed,  and  the  houses 
on  a  given  street  are  nearly  uniform  in  height,  excellent  sewer  ventila- 
tion may  be  secured  by  omitting  all  traps  in  the  house  drains,  carrying 
the  soil  pipe  up  with  a  free  opening  at  its  top  above  the  roof,  and  thus 
allowing  the  house  pipes  to  ventilate  the  sewer. 

But  where  the  sewers  are  badly  constructed — so  that  accumula- 
tions of  decomposing  filth  occur  at  certain  points — where  cesspool 
overflows  are  admitted  to  them,  and  where  the  houses  vary  much  in 
height,  so  that  the  top  of  the  soil  pipe  of  one  house  may  be  beneath 
the  level  of  the  windows  of  living  rooms  in  another,  it  is  not  expedient 
to  use  the  soil  pipes  as  ventilators,  and  it  is  better  to  prevent  this  by 
placing  a  trap  on  the  main  drain  between  the  house  and  the  sewer. 
When  this  is  done  the  usual  plan  is  to  provide  air  inlets  and  outlets  to 
the  sewer  by  means  of  openings  at  the  street  level,  placed  at  intervals 
of  three  or  four  hundred  feet  and  covered  with  gratings  ;  while  a 
separate  ventilation  is  provided  for  the  soil  pipe  by  means  of  a  fresh- 
air  inlet  placed  on  the  house  side  of  the  trap. 

Occasionally  there  is  a  demand  for  some  means  of  cooling  the 
fresh-air  supply  in  warm  weather,  as  in  legislative  assembly  halls,  in 
summer  theaters,  or  for  the  room  of  a  sick  person,  and  in  the  descrip- 
tion of  the  ventilating  appliances  of  some  buildings  it  is  stated  that 
provision  is  made  for  doing  this  by  blowing  the  air  over  ice  placed  on 
racks,  etc.  The  use  of  ice  for  this  purpose  is  a  very  expensive 
method.  It  was  tried  in  the  room  in  the  White  House  occupied  by 
President  Garfield,  in  July  and  August,  1881,  during  his  illness,  and 
with  a  36-inch  blower,  forcing  about  22,000  cubic  feet  of  air  per  hour 
over  ice  into  the  room,  the  temperature  was  lowered  5.4°  F.,  when 
the  outside  temperature  was  84.9°  F.,  and  about  436  pounds  of  ice 
were  melted  per  hour.  The  description  of  the  apparatus,  and  of  the 
results  obtained,  is  given  in  a  pamphlet  entitled  "  Reports  of  Officers 
of  the  Navy  on  Ventilating  and  Cooling  the  Executive  Mansion  during 
the  Illness  of  President  Garfield,"  8vo.,  Washington,  Government  Print- 
ing Office,  1882,  which  will  be  found  interesting  by  those  who  wish  to 
provide  such  an  apparatus  in  an  emergency. 

If  a  permanent  plant  for  this  purpose  be  desired,  some  form  of 
compressed  air  apparatus  in  which  the  heat  evolved  by  the  compres- 


HEATING    CONTRACTS.  493 

sion  of  the  air  is  removed  by  cold-water  pipes,  and  the  desired  coolness 
is  produced  by  the  expansion  of  the  air  will  probably  be  found  to  be 
the  most  satisfactory  and  economical.  It  should  be  remembered, 
however,  that  when  the  air  of  an  assembly  room  is  loaded  with  mois- 
ture the  introduction  of  cold  air  may  precipitate  this  moisture  and  pro- 
duce a  fog  or  cloud  if  there  is  dust  in  the  air.  This  was  actually  the 
result  of  one  experiment  of  blowing  cold  air  into  one  of  the  assembly 
halls  at  the  Capitol  in  Washington.  It  should  also  be  remembered 
that  there  is  danger  to  health  in  cooling  the  air  8  or  10  degrees  below 
that  of  the  outer  air.  A  plentiful  supply  of  air  is  usually  the  best 
method  to  secure  relief  from  the  feeling  of  excessive  heat. 

In  conclusion,  a  few  words  about  making  contracts  for  heating 
and  ventilating  apparatus,  and  about  the  means  for  securing  proper 
ventilation  for  public  buildings,  may  not  be  out  of  place.  The 
usual  mode  of  obtaining  bids  and  making  contracts  for  heating  and 
ventilating  apparatus  is  not  a  good  one,  and  it  is  not  surprising  that  it 
often  produces  unsatisfactory  results.  Contractors  for  heating  and 
ventilating  apparatus  are  invited,  or  are  permitted  to  make  their  own 
specifications  and  state  what  they  will  do  the  work  for,  the  only  thing 
required  by  the  architect  or  builder  being  that  "the  building  shall  be 
heated  by  steam  to  a  temperature  of  70°  F.  in  the  coldest  weather,"  to 
which  maybe  added  that,  "  satisfactory  ventilation  must  be  provided." 
The  work  is  then  given  to  the  lowest  bidder,  little  or  no  consideration 
being  given  to  the  relative  merits  of  the  different  schemes.  Even  if  the 
schemes  are  compared,  there  is  no  security  that  the  one  who  furnishes 
the  best  plan,  with  sufficient  details  to  judge  of  its  merits,  will  get  the 
contract.  His  figures  may  be  used  merely  to  fix  a  price  for  the  work, 
or  the  information  he  gives  may  be  used  to  prepare  specifications  for 
another  and  lower  bidder.  Competition  under  such  circumstances  is 
a  farce.  The  firms  which  employ  a  competent  engineer  and  can  be 
relied  on  for  good  work  have  learned  by  experience  that  it  is  useless  to 
employ  an  expert  to  make  plans  and  estimates  which  are  to  be  judged 
by  persons  who  know  nothing  about  the  matter,  and  who  will  simply 
look  at  the  item  of  cost. 

The  firms  which  are  specially  interested  in  some  particular  kind 
of  heating  apparatus,  propelling  or  exhaust  fan,  or  patent  system,  often 
have  a  blank  form  of  specification,  which  they  can  fill  in  in  half 
an  hour,  on  the  "cubic  space  to  be  heated"  principle,  and,  of 
course,  they  are  always  ready  to  compete  at  the  shortest  notice. 
But  the  best  plan  will  rarely,  if  ever,  be  the  cheapest  one  ;  in  fact,  it 
is  a  good  rule  to  exclude  at  once  the  lowest  bids  to  the  extent  of 


494  HEATING    CONTRACTS. 

one-fourth  of  the  total  number  of  bids.  What  is  wanted  is  to  get  the 
best,  or,  at  all  events,  thoroughly  good,  work  at  a  fair  price.  The 
essential  thing  to  secure  this  is  a  detailed  specification  with  plans, 
showing  for  each  room  the  position  and  size  of  flues  and  registers,  and 
of  such  direct  or  direct-indirect  radiators  as  may  be  desired,  and  the 
quantity  of  air  to  be  introduced  and  removed  per  hour,  and  also 
showing  the  location,  size,  and  material  of  boilers  or  heaters,  the  size 
and  location  of  mains,  and  the  size  and  location  of  indirect  heaters, 
coils  or  radiating  surfaces.  If  the  architect  wishes  to  employ  a  hot- 
blast  system,  or  to  have  plans  for  such  a  system  to  compete  with  the 
usual  methods,  he  should  specify  the  position  and  size  of  flues  and 
registers  for  each  room,  and  the  ordinary  and  maximum  velocity  at 
which  the  air  is  to  pass  through  each  register,  and  also  require  that 
means  be  supplied  for  regulating  the  temperature  of  the  air  in  each 
room  without  interfering  with  the  quantity  delivered,  and  then  call 
upon  firms  doing  this  class  of  work  to  submit  plans  showing  how  they 
propose  to  meet  these  requirements.  In  comparing  bids  on  such  plans 
with  those  on  plans  for  divided  radiating  surfaces,  whether  the  motive 
power  be  supplied  by  aspirating  flues  or  chimneys,  with  or  without 
accelerating  steam  coils,  or  by  propelling  or  aspirating  fans,  he  should 
consider  with  care  the  expense  of  running  the  different  forms  of  appa- 
ratus, including  the  salary  of  an  engineer,  etc.,  and  also  what  is  to  be 
done  to  supply  heat  in  case  the  blowing  apparatus  must  be  stopped  for 
repairs  in  cold  weather.  This  is  especially  important  in  a  building 
permanently  occupied,  such  as  a  hospital.  He  should  also  remember 
that  if  a  patented  apparatus,  or  one  that  necessitates  the  employment 
of  a  particular  piece  of  apparatus  made  only  by  one  firm,  is  accepted, 
there  will  be  no  possibility  of  competition  when  repairs  or  additions 
become  necessary,  and  that  five  or  ten  years  hence  it  may  be  very  diffi- 
cult to  obtain  the  peculiar  appliances  needed  for  such  repairs  or  addi- 
tions. I  do  not  mean  by  this  that  he  should  not  specify  for  particular 
patented  pieces  of  apparatus,  such  as  valves,  etc.,  but  that  he  should 
be  very  wary  about  accepting  any  so-called  "  system  of  ventilation  " 
which  is  controlled  by  a  single  firm. 

A  properly  drawn  specification  or  contract  will  give  the  number  of 
square  feet  of  radiating  surface  to  be  furnished.  Contractors  know 
that  architects  very  rarely  make  examinations  or  measurements  as  to  the 
amount  of  heating  surface  actua!4y,..furnisjied,  and  hence  unscrupulous 
men  do  not  hesitate  to  bid  low  and  reduce  the  quantity.  Moreover, 
as  has  been  pointed  out  in  the  chapter  on  radiators,  the  actual 
amount  of  heating  surface  in  most  patented  or  proprietary  cast-iron 


MANAGEMENT    OF    VENTILATION.  495 

radiators  is  from  20  to  30  per  cent,  less  than  that  which  is  claimed  for 
them. 

The  architect  should  assure  himself  by  evidence  other  than  that 
of  the  contractor,  if  he  cannot  make  the  examinations  and  measure- 
ments himself,  that  the  amount  of  heating  surface  contracted  for  has 
actually  been  furnished. 

In  the  chapter  on  schools  allusion  has  been  made  to  the  Massa- 
chusetts law  to  secure  proper  ventilation  and  sanitary  arrangements  of 
public  buildings.  The  idea  of  effecting  this  by  a  central  State  author- 
ity is  a  good  one,  for  it  will  certainly  not  be  done  by  local  authorities  ; 
but  it  is  hardly  to  be  expected  that  police  inspectors  will  be  able  to 
exercise  satisfactory  supervision  over  these  matters.  It  requires  the 
constant  service  of  a  competent  heating  engineer,  to  whom  all  plans 
for  the  heating  and  ventilation  of  the  schools,  asylums,  prisons  and 
other  buildings  constructed  and  maintained  at  public  expense,  whether 
State  or  municipal,  should  be  submitted  for  approval.  Such  an  engi- 
neer should  be  connected  with  the  State  Board  of  Health,  which  is  the 
proper  department  to  have  charge  of  matters  of  this  kind,  and  he 
should  not  be  connected  in  any  way  with  any  heating  firm  or  with  any 
patent  or  proprietary  apparatus  or  schemes. 

Finally. — I  wish  to  call  special  attention  to  the  fact  that  any 
system  of  combined  heating  and  ventilating  apparatus  requires  con- 
stant care  as  to  its  cleanliness,  preservation  and  adjustment  to  the 
requirements  of  the  inmates,  which  requirements  vary  with  the  season, 
the  direction  and  force  of  the  wind,  and  sometimes, with  the  hour  of 
the  day,  if  the  best  results  which  the  apparatus  is  capable  of  are  to 
be  obtained. 

The  most  wasteful  of  all  expenditures  for  a  public  building  is  to 
provide  an  elaborate  and  costly  apparatus  for  heating  and  ventilation, 
and  then  intrust  it  to  the  care  of  an  ignorant  and  careless  engineer, 
selected  not  on  account  of  his  knowledge  of  what  is  to  be  done  and 
how  to  do  it,  but  because  he  is  "  somebody's  nephew,"  or  is  an  "  active 
politician,"  or  is  "  unable  to  support  his  family." 


INDEX. 


ABBOTT  (Dr.  A.  C.),  v,  98. 

Abbott's  by-pass,  271. 

Academy  of  Music,  Baltimore,  393. 

Accelerating  coils,  148. 

Acoustics  an,d  ventilation,  370. 

Adhesion  of  air  to  surfaces,  197. 

Adler  &  Sullivan,  399. 

Agricola(G.),  26,  288,  294,  295. 

Air,  adhesion  of  277. 

Air,  analysis  of,  180, 

Air,  cooling,  357,  374»  3?8,  492. 

Air  currents,  testing  of,  169. 

Air  niters,  357. 

Air  filtration,  248,  459. 

Air,  heating  of,  210,  228. 

Air  inlets,  254. 

Air  mixing,  261. 

Air,  physics  of,  48. 

Air  supply  for  schools,  412. 

Air  supply,  quantity  of,  38,  120,  129. 

Air  supply,  quantity  of,  for  mines,  290. 

Air  supply,  sources  of,  247. 

Air  testers,  177. 

Air,  weight  of,  210. 

Air  ways  in  mines,  297. 

Alarm  thermometer,  416. 

Alhambra,  26. 

Ammonia,  82. 

Ammonia  in  the  air,  204. 

Amphitheater,  438. 

Anderson  on  hot-water  heating,  240. 

Andre  (G.  G.),  formula,  291. 

Anemometers,  162. 

Animals,  air  required  for,  130. 

Appold's  heat  regulator,  242. 

Aqueous  vapor,  46. 

Aqueous  vapor,  tension  of,  53. 

Archimedean  screw  ventilators,  287. 

Army  hospitals,  315. 

Arnott  (Neil),  35. 

Aspirating  fans,  157. 

Aspirating  flues,  147. 

Aspiration  systems,  274. 

Assembly  halls  or  rooms,  355. 

Atkinson's  co-efficient,  299. 

Atmosphere,  42. 

Auburn  system,  485. 

Automatic  heat  regulators,  240. 


BABCOCK  &  Wilcox  Co. ,  on  chimneys, 

143- 

Bacillus  tuberculosis,  19,  98. 
Bacteria,  25,  47,  108,  96. 
Bacteria  in  the  air,  206. 
Bagot's  formula,  291. 
Baker,  Smith  &  Co.,  radiator,  223. 
Baker,  Smith  &  Co.,  switch  valve,  262. 
Baldwin  (W.  J.),  39,  236,  434. 
Baldwin  on  hot- water  heating,  240. 
Baldwin's  rule  for  heating  surface, 

227. 

Baldwin's  switch  valves.  266,  268. 
Baltimore  (the  cruiser),  482. 
Baltimore  Academy  of  Music,  393. 
Barker's  patent,  286. 
Barnes  Hospital,  324,  327. 
Barometer,  50. 
Barrack  hospitals,  303. 
Barracks,  250,  350. 
Barracks,  cubic  space  in,  136. 
Berkeley  School,  439. 
Bernan  (W.),  27. 
Bibliography,  40. 
Bids,  493. 

Black  hole  of  Calcutta,  95. 
Blegdams  Hospital,  308. 
Blowers,  155. 
Bohm  (Dr.),  380. 
Boilers,  232. 
Bottle  ventilation,  146. 
Box  on  air  supply,  124. 
Bradford  Small-pox  Hospital,  304. 
Brazil,  air  of.  73. 
Bridgeport  Hospital,  266. 
Bridgeport  School,  418. 
Briggs  (R.),  38,  472. 
Briggs  (W.  R.),  418. 
Briggs  on  fans,  158. 
Bryn  Mawr  School,  433. 
Brown  Sequard,  92. 
Buffalo  Forge  Co.  on  blowers,  158. 
By-passes,  261. 

CAMBRIDGE  Hospital,  316. 
Capitol  at  Washington,  360. 
Car  ventilation,  481. 
Carbacidometer,  178. 


INDEX. 


497 


Carbonic  acid,  61. 

Carbonic  acid,  daily  fluctuation,  So. 

Carbonic  acid  excreted  from  lungs,  88. 

Carbonic  acid,  monthly  fluctuation,  81. 

Carbonic  acid  test,  171,  175. 

Carburetted  hydrogen,  288. 

Carnegie  Music  Hall,  372. 

Carnelley  &  Mackie's  method,  90,  198. 

Carrick  (W.  H.),  465- 

Casella's  anemometer,  163. 

Centrifugal  ventilators,  296. 

Chabannes,  Marquis  de,  33. 

Chamber  of  Deputies,  364,  371. 

Chemical  lung,  480. 

Chicago  House  of  Correction,  487. 

Chilton  Colliery,  296. 

Chimney,  aspirating,  488. 

Chimney  caps,  277. 

Chimney  top  ventilator,  281. 

Chimney  valves,  276. 

Chimneys,  138. 

Churches,  402. 

Circular  wards,  3-  6. 

Cisalpin's  chimney  top  ventilator,  281. 

Cities,  air  of,  65,  69. 

City  dwellings,  453. 

Closets,  462. 

Coal  mines,  289. 

Co-efficient  of  expansion,  48. 

College  of  Physicians  and  Surgeons, 
270,  434. 

Columbia  College  Library,  Lecture 
Room,  etc.,  151. 

Combe's  anemometer,  165. 

Combined  steam  and  hot-water  heat- 
ing, 317- 

Competition  in  bids,  493. 

Compressed  air  jets,  160. 

Contagious  diseases,  hospitals  for, 
302. 

Contracts,  493. 

Cooling  of  air,  357,  374.  378,  492. 

Copenhagen  theater,  400. 

Cornet,  19. 

Cow  stables.  131. 

Cowls,  279. 

Cowls,  tests  of,  282. 

Croton  aqueduct  tunnel,  478. 

Cubic  space,  133. 

Cubic  space  in  barracks,  350. 

Cubic  space  in  schools,  412. 

Current  splitting,  300. 

DAIRY  ventilation,  253. 

Dammann,  on  air  supply  for  stables, 

131- 

Dastre  and  Loye,  93. 

De  Chaumont,  on  air  supply,  134,  173, 

412. 
De  Chaumont,  on  moisture,  117. 


De  Lyle    St.    Martin's   chimney    top 
ventilator,  281. 

Desaguliers  (T.),  27. 

Desaguliers'  wheel,  30. 

Direct  radiation,  213. 

Dissecting  room,  438. 

Donkin's  formula,  133. 

Double  tube  ventilation,  284. 
|    Downward  ventilation,  362. 
I    Drying  rooms,  109. 
I    Drysdale  and  Hayward,  443. 

Dust,  98,  105. 

Dust  in  factories,  107. 

Dust  strainers,  248. 

Dwellings,  442. 

EARTH  heating,  250. 

Eastern  penitentiary,  488. 

Eayrs  (N.  W.),  479. 

Elliott  (W.  G.),  391. 

Elmira  prison,  485. 
|    Emerson  ventilator,  281. 
1    Empire  Theater,  Philadelphia,  399. 
I    Englewood  church,  408. 
|    Ewbank  and  Mott,  279. 

Exhaust  steam  heating,  234. 

Expired  air,  87,  93. 

Expired  air,  poison  in,  92. 

Explosive  mixtures,  113. 

I    FAN  in  Barnes  Hospital,  330. 
|    Fan  in  House  of  Commons,  30. 
j    Fans,  155,  324,  479,  482. 
j    Fans  for  mines,  293. 

Fans,  tests  of,  298. 

Felton  (Charles  E.),  487. 

Ferryboats,  484. 

Fifth   Avenue  Presbyterian   Church, 
N.  ¥.,402. 

Filters,  air,  248. 

Filtration  of  air,  357. 

Fire  rooms,  483. 

Fire  damp,  289. 

Fireplaces,  214. 

Fireplaces,  double,  217. 

Floor  space,  136. 

Floor  space  for  schools,  413. 

Flue  terminals,  281. 

Flues,  254. 

Fodor,  79,  83. 

Folsom  (Dr.  N.),  switch  valve,  265. 

Forces  producing  ventilation,  137. 

Fort  Sheridan  barracks,  351. 

Fort  Yuma,  115. 

Foul-air  flues,  273. 

Foul-air  registers,  255,273. 
1    Frankfort  Opera  House,  384. 
1    Fresh-air  inlets,  254. 

Frey,  80. 
,   Friction  of  air,  259. 


498 


INDEX. 


Fuess's  anemometer,  168. 
Fuller  (W.  A.),  453. 
Furnaces,  119,  215,  218. 
Furnaces  for  mines,  292. 

GARTNER  (J.),  484. 

Garfield  (President),  492. 

Garfield  School,  428. 

Gas,  illuminating,  96,  131. 

Gas  jets  for  ventilation,  147. 

Gauger  (N.),  27. 

Geneva  Theater,  401. 

George  (S.  L.),  462. 

Gillis  &  Geoghegan's  switch  valve,  261 . 

Glasgow  Infirmary,  249. 

Grain  (sweating),  489. 

Guibal  fan,  295. 

HABITATIONS,  442. 

Hales  (Stephen),  31. 

Halls  of  audience,  355. 

Hamburg  Hospital,  342. 

Harmattan,  115. 

Harmon  (Dr.  George  E.  H.),  483. 

Hazleton  Hospital,  324. 

Head  of  air,  299. 

Heat,  loss  of,  from  surfaces,  225,  226. 

Heat,  measures  of,  209. 

Heating.  208. 

Heating  surface,  225. 

Heating  surface,  Tredgold's  formula, 

34.  225. 

Hebrew  Temple,  Philadelphia,  406. 
Heger's  helix,  381. 
Hellyer  on  cowl  testing,  283. 
History  of  ventilation,  26. 
Hood's  formula  for  heating  surface, 

239- 

Hoosac  tunnel.  479. 
Horse-power,  233. 
Horses,  490. 

Horses,  air  supply  for,  130. 
Hospital,  heating  of,  229. 
Hospital  ventilation,  301. 
Hospitals,  301. 

Hot-blast  system,  157,  233,  400. 
Hot-water  heating,  238.  337,  444,  462. 
House  of  Commons,  356. 
House  of  Lords,  357. 
Houses  of  Parliament,  26,  35,  356. 
Humidity,  46. 

ILLUMINATING  agents,  95,  131. 
Inlets,  254. 
Insane  asylums,  346. 
Isolating  wards,  308. 

JACKSON  School,  422. 
Jeffreys  (Dr.),  250 
Jellett  (S.  A.),  406,  433. 


Johns  Hopkins  Hospital,  277,  308,  336. 
Johns     Hopkins       Hospital,     switch 

valve,  264. 
Joy  draft  tube  radiator,  426. 

KENESETH-!SRAEL,  406. 
Kew  test  of  cowls.  282. 

LABORATORY  of  Hygiene,  249. 
Lackawanna  prison,  488. 
Lannan  (Mr.),  366. 
Laundries,  in. 
Leeds'  theory,  213. 
Lenox  Lyceum,  376. 
Legislation  on  ventilation,  439. 
Legislative  halls,  355. 
Lehmann  &  Jessen,  93. 
Lessing  Theater,  401. 
Levy,  69. 

Lights,  effects  of.  203. 
Lincoln  (Dr.),  416,  419. 
Lincoln  (D.  F.),  475. 
Liverpool  tunnel,  479. 
Londonderry  steamer,  95. 
Lunge-Zeckendorf  method,  180. 

MACDONALD  ventilator,  284. 

McClurg  (General  A.  C.),  449. 

McCosh  Infirmary,  319. 

M'Kinnell's  double  tube,  284. 

Madison  Square  Theater,  391. 

Marker  (Max),  490 

Mains,  sizes  of,  233. 

Manchester  theaters,  379,  380. 

Marsh  gas,  289. 

Massachusetts  ventilation  law,  439. 

Measurement  of  ventilation,  170. 

Meikleham  (R.),  27. 

Mercer's  switch  valve,  266. 

Mersey  tunnel,  479. 

Metropolitan  Opera  House,  386. 

Miantonomoh,  483. 

Micro-organisms  in  air,  92. 

Miller,  Captain,  354. 

Milne's  rule  for  chimneys,  142. 

Miners'  Hospital,  324. 

Mines,  197. 

Mines,  ventilation  of,  288. 

Minimetric  method,  180. 

Mixing  register,  267. 

Mixing  valve,  320. 

Model    to  show   natural   ventilation, 

60. 

Moisture,  46,  52,  108,  114. 
Mont  Cenis  tunnel,  478. 
Montgolfier's  law,  139. 
Moses  Taylor  Hospital,  267. 
Morin  on  air  supply,  126. 
Mountain  air,  76. 
Miintz,  &  Aubin,  74. 


INDEX. 


499 


NEALE  (Dr.  R.),  480. 

New  Castle  County  Asylum,  346. 

New  York  Hospital,  333. 

New  York  Music  Hall,  372. 

New  York  State  Reformatory,  485. 

Newton's  switch  valve,  263. 

Nice,  theater  at,  401. 

Nichols  (W.  R.),  414,  481. 

Norris  (R.  Van  A.),  295. 

OCTAGON  wards,  341. 

Odors  and  air  supply,  121. 

Onderdonk  (C.  S.),  445- 

Opera  House,  Vienna,  380. 

Ophir,  484. 

Organic    matter,    determination    of, 

198. 

Organic  matter  in  air,  89,  121. 
Orthopaedic  Hospital,  268. 
Outlet  ventilators,  277. 
Outlets,  255. 
Oxygen,  44. 
Oxygen  absorbed,  88. 
Ozone,  43. 

PAPER  mills,  489. 

Peclet's  formula  for  loss  of  heat,  226. 

Pendulum  anemometer,  166. 

Pennsylvania  law  for  mines,  290. 

Pentonville  systems,  485. 

Perreau  (L.),  488. 

Pest  houses,  302. 

Petri's  method,  172. 

Pettenkofer  on  air  supply,  123. 

Pettenkofer's  laboratory,  160. 

Pettenkofer's  method,  183. 

Pfeiffer  (Carl),  402. 

Philadelphia  Steam  Engineering  Co., 

399- 

Phthisis,  19,  98. 
Pickhardt  (Mr.),  stable,  491. 
Planat's  aspirating  systems,  274. 
Pond(Capt.  Geo.  E.),  351. 
Post  (George  B.),  333- 
Post  hospitals,  315. 
Prentice  Co.  (L.  H.).  399,  449,  453- 
Pressure  gauges    166,  168. 
Princeton  Hospital,  319. 
Prisons,  484. 

Pueblo  Opera  House,  393. 
Putnam  on  fireplaces,  214. 
Putzeys  (F.),  354. 

QUANTITY  of  air  required,  120,  129. 

RADCLIFFE  (Dr.  J.  N.),  285. 
Radiating  surface,  495. 
Radiating  surface  formula,  409. 
Radiation,  212. 
Radiator,  sectional,  222. 


Radiators,  235. 

Radiators,  by-pass,  261. 

Radiators,  indirect,  348. 

Radiators,  location  of,  231. 

Railway  cars,  481. 

Railway  tunnels,  478. 

Rain,  effect  on  air,  73. 

Ramsbottom  (Mr.),  479. 

Reed  (Dr.  R.  Harvey),  481. 

Registers,  254,  258. 

Reid  (David  B.),  35. 

Reiset's  method,  196. 

Remsen's  method  for  ammonia,  205. 

Remsen's  method  for  organic  matter, 

S9-    . 

Respiration,  85. 
Respiratory  quotient,  88. 
Rhode  Island  State  Prison. 
Root's  blower,  296. 
Roschdestwensky  Hospital,  303. 
Rosebrugh's  window  ventilator,  259. 
Roster,  79,  81 . 
Royal  Theater,  Copenhagen,  400. 

SACHSEN  (the  corvette),  484. 
St.  Louis  tunnel,  479. 
St.  Petersburgh  City  Hospital,  303 
San  Francisco  (the  cruiser),  482,  483. 
Sanderson  (Dr.  Burdon),  304. 
Saprophytes,  97. 
Savart  (F.),  277. 
Scheduling  rooms,  226. 
Schools,  410. 
Sea  air,  70,  71,  72,  74. 
Sedgwick's  method  for  bacteria,  206. 
Seidel's  formula,  123. 
Sewer  air,  99. 
Sewer  ventilation,  491. 
Shepard's  patent,  253. 
Sheringham  valve,  257. 
Ships,  481. 
Siderosis,  106. 
Singing  coal,  289. 
Skeel  and  Nason,  404. 
Sloane  (Prof.  W.  M.),  444, 
Small-pox  hospitals,  302,  304. 
Smart  (Dr.  Charles),  369. 
Smith  (Dr.  F.),  490. 
Smoke  test,  169. 
Smoky  chimneys,  144. 
Soil  air,  102. 
Soil  pipe  ventilation,  49 1. 
Somasco  (M.),  468. 
Sorbonne,  Paris,  371. 
Specifications,  224,  493. 
Splits,  300. 
Spray  screens,  250. 
Stables,  131,  136,  489,  490. 
Steam  Engineering  Co.,  Philadelphia 
4fA  433- 


5oo 


INDEX. 


State  heating  engineer,  495. 
Steam  heating,  220. 
Steam   and  hot-water  heating   com- 
bined, 316. 
Steamships,  482. 
Storehouses,  489. 
Storer  &  Pearson,  66. 
Stoves,  471. 

Sturtevant  blowers,  482. 
Sub-earth  ventilation,  253. 
Supervision  of  ventilation,  495. 
Sutton  (Samuel),  32. 
Switch  valves,  261. 
Syphons,  286,  463. 
Szydlowski's  method,  192. 

TEMPERATURE  correction,  50. 
Temperature,  regulation  of,  240,  243, 

261. 

Theaters,  379. 
Thermostats,  243,  377. 
Thorpe,  71,  73. 
Tissandier,  76. 
Tobin's  tubes,  258,  333. 
Transports,  484. 
Tredgold  (T.),  33. 
Tredgold  on  drying  rooms,   109. 
Tredgold's  rule  for  chimneys,  142. 
Tredgold's  rule  for  heating  surface, 

34,  225. 

Trelat  (M.),  213,  364-  3?i- 
Trowbridge,  formula  for  accelerating 

coils,  149. 

Trowbridge,, rule  for  chimneys,   144. 
Tudor  (Frederic),  386. 
Tudor's  valve,  223. 


Tunnels,  478. 
Twin  air  ducts,  270. 

UFFELMANN,  75. 
Upcast  shafts,  275. 
Upward  ventilation,  363. 

VAN  REYPEN  (Dr.  W.  K.),  483. 
Van  Slooten,  90. 
Ventilation,  definition  of,  33. 
Ventilation,     forces     concerned     in 

137- 
Vienna  Opera  House,  380. 

WALKER  (T.  H.),  44. 

Wall  heating,  371,  468. 

Wall  surface,  loss  of  heat  from,  228. 

Water-closet  ventilation,  460. 

Water  hammer,  224. 

Water-jet  ventilator,  160. 

Wetherell  Report,  39,  360. 

White  House,  cooling  of,  492,  493. 

Wilkinson's  patent,  253. 

Wilson  (Capt.  T.  D.),  483. 

Winans  (T.),  24. 

Wind,  138. 

Window  inlets,  259. 

Windows,  loss  of  heat  from,  228. 

Wistar  (Isaac  J.),  45. 

Wolpert's  air  tester,  177. 

Wolpert's  carbacidometer,  178. 

Work  (Mr.),  stable,  490. 

Workshops,  488,  489. 

Wyman  (Dr.  Morrill),  38,  280,  319. 

YORKTOWN  (the  gunboat),  483. 


ADVERTISEMENTS. 


SRECORD 


(Prior  to  1887  The 
S anit a ry  Engi- 
neer}, because  of 
the  prominence  it 
gives  to  problems 
of  Building  and 
Sanitary  Engineer- 
ing, is  in  these  days 

a  most  valuable  aid  to  every  Architect,  Heating  and  Ventilating  Engineer, 
and  to  every  person  who  is  called  upon  to  design  and  prepare  specifications 
for  important  modern  buildings,  and  to  those  who  are  their  custodians  after 
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THP  BUFFALO  "FAN"  SYSTEM 


OF 


Heating^Ventilation. 


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The  EMPIRE  THEATRE,  Philadelphia,  Pa. 

The  LOUISVILLE  AND  NASHVILLE  STATION,  Louisville,   Ky. 

The  WILLIAMS  COUNTY  COURT  HOUSE,  Bryan,  Ohio. 

The  WAYNE  COUNTY   COURT  HOUSE,  Richmond,  Ind. 

The  Y.   M.  C.  A.,  Cincinnati,  Ohio. 

The  BUFFALO  STATE  INSANE  HOSPITAL,  Buffalo. 

The  ASYLUM  FOR  INSANE,  Spencer,  W.  Va. 

The  ST.   MARY'S  (CATHOLIC)  HOSPITAL,  Saginaw,  Mich. 

The  WESLEY  M.  E.  CHURCH,  Minneapolis,  Minn. 

The  OHIO  STATE  MANUAL  TRAINING  SCHOOL,  Columbus,  Ohio. 

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HOT-WATER  HEATING  AND  FITTING; 

OR; 

WARMING  BUILDINGS  BY   HOT-WATER. 

A   DESCRIPTION   OF 

Modern   Hot-Water  Heating   Apparatus — The    Methods    of  their 
Constrttction  and  the  Principles  involved. 

WITH  OVER  Two  HUNDRED  ILLUSTRATIONS,  DIAGRAMS  AND  TABLES. 


BY  WILLIAM  J.  BALDWIN,  M.  Am.  Soc.  C.  £., 

Member  American  Society  Mechanical  Engineers, 

AUTHOR  OF   "STEAM-HEATING  FOR   BUILDINGS,"   ETC.,    ETC. 


Grapmcal  methods  are  used  to  illustrate  many  of  the  important  principles  that  are 
to  be  remembered  by  the  Hot- Water  Engineer. 

The  volume  is  8vo.,  of  385  pages,  besides  the  index  ;  handsomely  bound 
in  cloth,  and  will  be  sent  postpaid  on  receipt  of  $4.00- 

Among  the  questions  treated  are  the  following  : 

Laws  of  Hot- Water  Circulation. 

Flow  of  Water  in  the  Pipes  of  an  Apparatus. 

Graphical  Illustration  of  the  Expansion  of  Water. 

Graphical  Illustration  of  the  Theoretical  Velocity  of  Water  in  Flow- 
Pipes. 

Efflux  of  Water  Through  Apertures. 

Passage  of  Water  Through  Short  Parallel  Pipes. 

Passage  of  Water  Through  Long  Pipes. 

Friction  of  Water  in  Long  Pipes. 

Quantity  of  Water  that  will  Pass  through  Pipes  under  Different  Press- 
ures. 

Diminution  of  the  Flow  ot  Water  by  Friction  in  Long  Pipes. 

Loss  of  Pressure  by  Friction  of  Elbows  and  Fittings. 

How  the  Friction  of  Elbows  and  Fittings  maybe  Reduced  to  a  Minimum. 

Flow  of  Water  through  the  Mains  of  an  Apparatus,  Considered  under 
its  Various  Practical  Conditions. 

How  to  Find  the  Total  Head  Required  when  the  Quantity  of  Water  to 
be  Passed  and  the  Size  and  Length  of  the  Pipes  are  Known. 

How  to  Find  the  Quantity  of  Water  in  U.  S.  Gallons,  that  will  Pas^s 
through  a  Pipe,  when  the  Total  Head  and  Length  and  the  Diameter 
of  the  Pipe  is  Known. 

r  o  Find  the  Diameter  of  the  Pipes  for  a  Given  Passage  of  Water. 

How  to  Find  the  Direct  Radiating  Surface  required  for  Buildings. 


How  Heat  is  Lost  from  the  Rooms  of  a  Building. 

Simple  Formula  for  Finding  the  Radiating  Surfaces  for  Buildings. 

Experiments  by  Different  Authorities  on  Radiating  Surfaces. 

To  Find  the  Amount  of  Water  that  should  Pass  through  a  Radiator  foi 
a  Certain  Duty. 

How  to  Determine  the  Size  of  Inlet  and  Outlet  Pipes  for   Hot- Water 

Radiators. 

iagrams  Giving  Graphical  Methods   for  Finding  the  Diameters  and 
Lengths  of  Flow  and  Return  Pipes  for  Hot-Water  Apparatus. 

Proportioning  Coils  and  Radiators  of  an  Apparatus  for  Direct  Radiation. 

I  Ascription  of  Different  Systems  of  Piping  in  Use. 

Proportioning  an  Apparatus  for  Indirect  Heating. 

Illustrations  of  Boilers. 

Hot- Water  Heating  in  the  State,  War,  and  Navy  Department  Building. 

Hot- Water  Heating  in  Private  Residences. 

Boilers  Used  for  Hot- Water  Heating. 

Direct  Radiators  Used  for  Hot-Water  Heating. 

Indirect  Radiators  Used  for  Hot-Water  Heating. 

The  Effect  of  Air-Traps  in  Hot-Water  Pipes. 

Expansion  Tanks — and  How  they  should  be  Prepared. 

Danger  of  Closed  Expansion  Tanks. 

The  Various  Valves  Used  for  Hot-Water  Heating. 

Air- Vents  Used  for  Hot- Water  Radiators. 

Automatic  Regulators  Used  in  Hot- Water  Heating. 

Special  Fittings  for  Hot-Water  Heating. 

How  to  Conduct  Tests  of  Hot- Water  Radiators. 

Method  of  Connecting  Thermometers  with  Hot-Water  Pipes  and 
Radiators. 

Tables  of  Contents  of  the  Pipes  of  an  Apparatus. 

Table  of  Co-efficients  of  the  Expansion  of  Water  from  Various  Sources, 
With  an  Ample  Table  of  Contents  from  which  the  above  Items 
were  Selected ;  also  an  Alphabetically  Arranged  Index,  the  Whole 
Containing  a  Large  Amount  of  Useful  Information  of  Great  Value 
to  the  Engineer,  Architect,  Mechanic  and  Householder.  No  Archi- 
tect, Engineer,  Steam-Fitter  or  Plumber  throughout  the  United 
States  should  be  without  a  copy  of  this  book.  It  is  written  in  the 
simple  style  of  Mr.  Baldwin's  former  book,  "  Steam  Heating  for 
Buildings,"  and  is  within  the  ready  comprehension  of  all. 


Address,  BOOK  DEPARTMENT,  Sent  Post-paid  for  $4.00. 

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A  FACT  WORTH  CONSIDERING. 

THE  MEYER-SNIFFEN  CO.,  the  manufacturers 
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STEAM-HEATING  PROBLEMS; 


OR, 


Questions,  Answers  and  ^Descriptions 

to  Steam- Heating  and  Steam- Fitting, 


FROM 


THE    ENGINEERING   RECORD, 

ESTABLISHED   1877. 

(Prior  to  1887,  THE  SANITARY  ENGINEER.) 


With  iog  Illustrations. 


PREFACE. 

THE  ENGINEERING  RECORD,  while  devoted  to  Engineering,  Architecture,  Con- 
struction, and  Sanitation,  has  always  made  a  special  feature  of  its  departments  of  Steam 
and  Hot-Water  Heating,  in  which  a  great  variety  of  questions  have  been  answered  and 
descriptions  of  the  work  in  various  buildings  have  been  given.  The  favor 
with  which  a  recent  publication  from  this  office,  entitled  "Plumbing  and  House- 
Drainage  Problems,  "has  been  received  suggested  the  publication  of "  STEAM-HEATING 
PROBLEMS,"  which,  though  dealing  with  another  branch  of  industry,  is  similar  in 
character.  It  consists  of  a  selection  from  the  pages  of  THE  ENGINEERING  RECORD 
of  questions  and  answers,  besides  comments  on  various  problems  met  with  in  the  design- 
ing and  construction  of  steam-heating  apparatus,  and  descriptions  of  steam-heating 
work  in  notable  buildings. 

It  is  hoped  that  this  book  will  prove  useful  to  those  who  design,  construct,  and 
have  the  charge  of  steam-heating  apparatus. 


CONTENTS: 


BOILERS. 


. 

Where  a  test-gauge  should  be  applied  to  a  boiler. 

Domes  on  boilers-  whether  they  are  necessary  or 
not. 

Expansion  of  water  in  boilers. 

Cast  -vs.  wrought  iron  for  nozzles  and  magazines 
of  house-heating  boilers. 

Pipe-connections  to  boilers. 

Passing  boiler-pipes  through  walls  ;  how  to  pre- 
vent breakage  by  settlement. 

Suffocation  of  workmen  in  boilers. 

Heating-boilers.     (A  problem.) 

A  detachable  boiler-lug. 

Isolating- valve  for  steam-main  of  boilers. 

On  the  effect  of  oil  in  boilers. 

Iron  rivets  and  steel  boiler-plates. 

Proportions  for  rivets  for  boiler-plates. 

Is  there  any  danger  in  using  water  continuously 
in  boilers? 

Accident  with  connected  boilers. 

A  supposed  case  of  charring  wood  by  steam-pipes. 

Domestic  boilers  warmed  by  steam. 

VALUE  OF  HEATING-SURFACES. 

Computing  the  amount  of  radiator-surface  for 
warming  buildings  by  hot  water. 


Calculating  the  radiating-surface  for  heating 
buildings— the  saving  of  double-glazed  win- 
dows. 

Amount  of  heating-surface  required  in  hot-water 
apparatus  boilers  and  in  steam-apparatus 
boilers. 

Calculating  the  amount  of  radiating-surface  for  a 
given  room. 

How  much  heating-surface  will  a  steam-pipe  of 
given  size  supply  ? 

Coiis  vs.  radiators  and  size  of  boiler  to  heat  a 
given  building. 

Calculating  the  amount  of  heating-surface. 

Computing  the  cost  of  steam  for  warming. 

RADIATORS  AND  HEATERS. 

A  woman's  method  of  regulating  a  radiator  (cov- 
ering it  with  a  cosey). 

Improper  position  of  radiator- valves. 

Hot-water  radiator  for  private  houses. 

Remedying  air-binding  of  box-coils. 

How  to  use  a  stove  as  a  hot-water  heater. 

"  Plane  "  vs.  "Plain  "  as  a  term  as  applied  to  out- 
side surface  of  radiators. 

Relative  value  of  pipe  on  cast-iron  heating  sur- 
face. 

Relative  value  of  pip*-  on  steam-coils. 


STEAM-HEATING  PROBLEMS. 


Warming  churches  (plan  of  placing  a  coil  in  each 

pew). 
Warming  churches. 

PIPE  AND  FITTING. 

Steam-heating  work— good  and  indifferent. 

Piping  adjacent  buildings:  pumps  vs.  steam- 
traps. 

True  diameters  and  weights  of  standard  pipes. 

Expansion  of  pipes  of  various  metals. 

Expansion  of  steam-pipes. 

Advantages  claimed  for  overhead  piping. 

Position  of  valves  on  steam-riser  connection. 

Cause  of  noise  in  steam-pipes. 

One-pipe  system  of  steam-heating. 

How  to  heat  several  adjacent  buildings  with  a 
single  apparatus. 

Patents  on  Mills'  system  of  steam-heating. 

Air-binding  in  return  steam-pipes. 

Air-binding  in  return  steam-pipes,  and  methods 
to  overcome  it. 

VENTILATION. 

Size  of  registers  to  heat  certain  rooms. 
Determining  the  size  of  hot-air  flues. 
Window  ventilation. 
Removing  vapor  from  dye-house. 
Ventilation  of  Cunard  steamer  "Umbria." 
Calculating  sizes  of  flues  and  registers. 
On  methods  of  removing  air  from  between  ceiling 
and  roof  of  a  church. 

STEAM. 

Economy  of  using  exhaust  steam  for  heat- 
ing. 

Heat  of  steam  for  different  conditions. 

Superheating  steam  by  the  use  of  coils. 

Effect  of  using  a  small  pipe  for  exhaust  steam- 
heating. 

Explosion  of  a  steam-table. 

CUTTING     NIPPLES    AND    BENDING 
PIPES. 

Cutting    large    nipples— large    in  diameter  and 

short  in  length. 
Cutting  crooked  threads. 
Cutting  a  close  nipple   out  of  a  coupling  after  a 

thread  is  cut. 
Bending  pipe. 
Cutting  large  nipples. 
Cutting  various  sizes  of  thread  with  a  solid  die. 

RAISING  WATER  AUTOMATICALLY. 

Contrivance  for  raising  water  in  high  buildings. 
Criticism   of    the    foregoing  and    description    of 
another  device  for  a  similar  purpose. 

MOISTURE  ON  WALLS,  ETC. 

Cause  and  prevention  of  moisture  on  walls. 
Effect  of  moisture  on  sensible  temperature. 

MISCELLANEOUS. 

Heating  water  in  large  tanks. 

Heating  water  for  large  institutions  and  high  city 

buildings. 
Questions  relating  to  water-tanks. 


Faulty  elevator-pump  connections. 

On  heating  several  buildings  from  one  source. 

Coal-tar  coating  lor  water-pipe. 

Filters  for  feeding  house- boilers.  Other  means 
of  clarifying  water. 

Testing  gas-pioes  for  leaks  and  making  pipe- 
joints. 

Will  boiling  drinking-water  purify  it? 

Differential  rams  for  testing  fittings  and  valves. 

Percentage  of  ashes  in  coal. 

Automatic  pump-governor. 

Cast-iron  safe  for  steam-radiators. 

Methods  of  graduating  radiator  service  according 
to  the  weather. 

Preventing  fall  of  spray  from  steam-exhaust 
pipes. 

Exhaust-condenser  for  preventing  fall  of  spray 
from  steam-exhaust  pipes. 

Steam-heating  apparatus  and  plenum  (ventila- 
tion), system  in  Kalamazoo  Insane  Asylum. 

Heating  and  ventilation  of  a  prison. 

Amount  of  heat  due  to  condensation  of  water. 

Expansion-joints . 

Resetting  of  house-heating  boilers--a  possible 
saving  of  fuel. 

How  to  find  the  water-line  of  boilers  and  position 
of  try-cocks. 

Low-pressure  hot-water  system  for  heating 
buildings  in  England  (comments  by  The 
Sanitary  Engineer). 

Steam-heating  apparatus  in  Manhattan  Com- 
pany's  and  Merchants'  Bank  Building,  New 
York. 

Boilers  in  Manhattan  Company's  and  Merchants' 
Bank  Building,  with  extracts  Jrom  specifica- 
tions. 

Steam-heating  apparatus   in  Mutual  Life  Insur- 
ance Building  on  Broadway. 
The  setting  of  boilers  in  Tribune   Building,  New 

York. 
Warming  and   ventilation   of  West  Presbyterian 

Church,  New  York  City. 

Principles  of  heating-apparatus,  Fine  Arts  Exhi- 
bition Building,  Copenhagen. 

Warming  and  ventilation  of  Opera-House  at 
Ogdensburg,  N.  Y. 

Systems  of  heating  houses  in  Germany  and 
Austria. 

Steam-pipes  under  New  York  streets — difference 
between  two  systems  adopted. 

Some  details  of  steam  and  ventilating  apparatus 
used  on  the  continent  of  Europe. 

MISCELLANEOUS  QUESTIONS. 

Applying  traps  to  gravity  steam-apparatus. 
Expansion  of  brass  and  iron  pipe. 
Connecting  steam  and  return  risers  at  their  tops. 
Power  used  in  running  hydraulic  elevators. 
On  melting  snow  in  the  streets  by  steam. 
Action  of  ashe?  street  fillings  on  iron  pipes. 
Arrangement  of  steam-coils  for  heating  oil-stills. 
Converting  a  steam-apparatus   into  a  hot-water 

apparatus  and  back  again. 
Condensation  per  foot  of  steam-main  when  laid 

under  ground. 
Oil  in  boilers  from  exhaust  steam,  and  methods 

of  prevention. 


Address,  BOOK  DEPARTMENT,  Sent  Post-paid  on  Receipt  of  3.00. 

THE    ENGINEERING    RECORD, 

p.  o.  BOX  3037.  277  PEARL  STREET,  NEW  YORK. 


THE  SMITH 
HOT  BLAST 
APPARATUS 


For  Heating 
and  Ventilating 
Buildings 
of  All  Kinds. 


MANUFACTURED   BY 


THE  HUYETT  &  SMITH  MFG.  Co., 

HEATING  AND  VENTILATING   ENGINEERS. 

CHICAGO,  Main  Office  and  Works : 

DETROIT,  MICHIGAN. 


NEW  YORK,  BOSTON. 


.  -  -  FORTY  YEARS  OF  UNINTERRUPTED  SUCCESS.  - 

—  THE  - 

DUNNING  BOILER. 

MADE  OF  WROUGHT-!RON  OR  STEEL. 

For  Steam  or  Hot-  Water  Heating 
with  fMagaqine  or  Surface  Feed. 


TUADE  iMAUK. 


ALL  THE  LATEST 
IMPROVEMENTS. 


18,000 


IN  USE. 


Manufact-  j^EW  YORK  QENTRAL 


ured  by 


15  N.  EXCHANGE  ST. 
GENEVA,  N.  Y. 


W.  F.  PORTER  &  Co.. 

.  .  Manufacturers  of  the  Page  Steam  and  Heating 

Hot-Water  Heaters,  Cast-iron  Radiation,  Contractors 

Pressure    Regulators,   Steam    Traps,   Oil  and 

Separators  and  Steam  Specialties.    .    .    .  Engineers. 

Office:  210  THIRD  STREET,  SOUTH, 

Factory:  NINTH  STREET  &  NINTH  AVENUE,  S.  E., 

MINNEAPOLIS,  MINN. 

Estimates  Jor   Heating  and    ['entilation    Furnished. 
Send  lor  Catalogue. 


PREACHING  IS  GOOD 
BUT  PRACTICE  IS  BETTER. 


Theory  is  excellent  as  a  study,  but  intangible  and 
useless,  until  proven  by  and  embodied  in  success- 
ful practice. 


IF  YOU  WISH^  CERTA I N 
RESULTS  IN  VENTILATION 


you  must  insist  that  he  who  PLAKS  shall  also  GUAR- 
ANTEE SUCCESS,  supporting  his  guarantee,  not  with 
official  position,  not  with  the  alphabet  as  an  appen- 
dix to  his  name,  but  with  AMPLE  HONUS  and  sureties. 


WE  OFFER  OUR  SERVICES 


as  Engineers  for  the  Ventilation  and  Warming  of 
any  class  of  public  buildings,  for  which  we  fur- 
nish PLANS  and  SPECIFICATIONS,  SKILLED  SUPER- 
VISION and  BONDS  insuring  success.  We  prove  our 
theory  by  showing  you  our  work. 


gMITH  J.JEATING  AND  yENTILATING  QO. 

KXCHANGE    BUILDING,   BOSTON,   Mass. 


7" HE  DAVIDSON  VENTILAT1NG  FAN  C0- 


MANUFACTURERS  OK 


rVLOWERS\  jyjOTORS  AND 


ENGINEERS  and  CONTRACTORS. 

-  -Estimates  and  Specifications  Cheerfully  Furnished. 


MAIN  OFFICH: 

Cor.   OLIVER  &  MILK  STREETS, 


BOSTON,  MASS.  •  I  I  "2  ]-    *ERTY  STREET. 


NEW  YORK  CITY   OFFICE: 


MANUFACTURERS  OF  THE 


BLACKMAN  VENTILATING  FAN 


VENTILATING    ENGINEERS  AND  CONTRACTORS 


Co. 

E.  G.  BARRATT,  PHES.  1O22  THE  ROOKERY,  CHICAGO 

:   :  :    We  prepare  Plans,  Specifications,  etc.,  and  erect  Ventilating 
Apparatus  in  all  parts  of  the  Country.     Correspondence  Solicited. 


Some  Details  of  Water-  Works 
Construction. 

By  W.  R.  BILLINGS,  Superintendent  of  Water-Works  at  Taunton,  Mass. 
WITH  ILLUSTRATIONS  FROM  SKETCHES  BY  THE  AUTHOR. 


INTRODUCTORY  NOTE. 

Some  questions  addressed  to  the  Editor  of  THE  ENGINEERING 
RECORD  by  persons  in  the  employ  of  new  water-works  indicated  that  a 
short  series  of  practical  articles  on  the  Details  of  Constructing  a  Water- 
Works  Plant  would  be  of  value  ;  and,  at  the  suggestion  of  the  Editor, 
the  preparation  of  these  papers  was  undertaken  for  the  columns  of 
that  journal.  The  task  has  been  an  easy  and  agreeable  one,  and  now, 
in  a  more  convenient  form  than  is  afforded  by  the  columns  of  the  paper, 
these  notes  of  actual  experience  are  offered  to  the  water-works 
fraternity,  with  the  belief  that  they  may  be  of  assistance  to  beginners 
and  of  some  interest  to  all. 


TABLE  OF  CONTENTS. 

CHAPTER  I.— MAIN  PIPES—  CHAPTER  IV.  —  PIPE-LAYING    AND 

Materials—  Cast-iron—  Cement-Lined  JOINT-MAKING- 

Wrought    Iron  -  Salt-Glazed    Clay—  Laying  Cement-Lined  Pipe-"  Mud  " 

Thickness  of  Sheet  Metal— Methods  of  Bell    and     Spigot  —  Yarn  —  Lead  — 

Lining— List   of   Tools— Tool-Box-  Jointers— Roll— Calking— Strength  of 

Derrick— Calking   Tools—  Furnace—  Joints— Quantity  of  Lead. 
Transportation — Handling  Pipe — Cost 

of  Carting— Distributing  Pipe.  CHAPTER  V.— HYDRANTS,    GATES, 

CHAPTER  II.— FIELD  WORK—  AND  SPECIALS- 
Engineering  or   None — Pipe   Plans — 

Special   Pipe— Laying  out  a  Line—  CHAPTER  VI.— SERVICE  PIPES— 

Width  and  Depth  of  Trench— Time-  Definition  —  Materials  —  Lead     vs. 

Keeping  Book— Disposition  of  Dirt—  Wrought   Iron  — Tapping   Mains   for 

I  unnelmg— Sheet  Piling.  Services— Different  Joints—  Compres- 

CHAPTER  III.— TRENCHING    AND  sion  Union— Cup. 
PIPE-LAYING- 

Caving  -  Tunneling  -  Bell-Holes  -  ^N^ME^S*  R  V  '  C  E"P  '  P  E  S 
Stony  Trenches— Feathers  and  Wedges 

—  Blasting — Rocks  and  Water —  Wiped  Joints  and  Cup-Joints — The 
Laying  Cast-Iron  Pipe — Derrick  Gang  Lawrence  Air-Pump — Wire-drawn  Sol- 
— Handling  the  Derrick — Skids — Ob-  der — Weight  of  Lead  Service-Pipe— 
structions  Left  in  Pipes — Laying  Pipe  Tapping  Wrought-Iron  Mains  —  Ser- 
in Quicksand — Cutting  Pipe.  vice-Boxes — Meter?. 

Large  8vo.  Cloth, .$2-00 
Address,  BOOK  DEPARTMENT, 

THE    ENGINEERING    RECORD. 

P.  o.  Box  3037.  277  PEARL  STREET,  NEW  YORK. 


STEAM 

DAMPER 

REGULATOR 


ELEVATOR 
PRESSURE 
REGULATOR 

For  controlling  Ele- 
vator Pumps  auto- 
matically by  water 
pressure.  Also  used 
as  a  By-Pass  Valve. 


REDUCING  VALVES 

For  reducing  and  maintaining 
an  even  steam  or  air  pressure. 
Standard  on  over  100  railroads 
and  all  large  steam  plants. 


Vis; 


MASON 

REGULATOR 

COMPANY, 

BOSTON,  MASS.,  U.S.  A. 


Send  for 

Catalogue 

and 

List  of 

Popular 

Engineer- 

Me 

Series. 


WATER  TOWER,  PUMPING  AND 
POWER  STATION  DESIGNS. 

BOUND         THE   ENGINEERING   RECORD'S 

IN  CLOTH,        PRIZE  DESIGNS,  SUGGESTIVE  FOR 

WATER  TOWERS,  PUMPING  AND  POWER  STATIONS. 


ADDRESS,  BOOK  DEPARTMENT, 

THE  ENGINEERING  RECORD, 

(Sent  Post -Paid  on  Receipt  of  Price.)  277   PEARL  STREET,  NEW  YORK. 


NEW  YORK. 


PHILADELPHIA. 


PROVIDENCE. 


THE  H.  B.  SMITH  CO., 

MANUFACTURERS    OF 

:  AND  :  \YATER  BEATING  APPARATUS 

FOR  PUBLIC  BUILDINGS  AND  PRIVATE    RESIDENCES. 


MERCER'S  PATENT  IMPROVED 
SECTIONAL  BOILER 

FOR   HOT-WATER   AND   STEAM   HEATING 

ADAPTED  :  FOR  :  HARD  :  OR  :  SOFT  :  COAL 


Gold's  Improved  Sectional  Boilers. 
Mills'  Patent  Safety  Sectional  Boilers. 
Union,    Royal,    Imperial   and    Champion 

Union  Hot-  Water  Radiators. 
Gold's  Indirect  Pin  Radiators. 
Breckinridge's  Patent  Automatic  Air 

Valves. 


SEND  FOR  CATALOGUES. 


MERCER  BOILER. 


OFFICE 
AND   WAREROOMS : 


&   1  37  CENTRE  ST.,  N.  Y. 


BARTLETT,  HAYWARD  &  CO., 

BALTIMORE,    MD. 

ENGINEERS  xWD  CONTRACTORS. 


MANUFACTURERS   OF 


Steam  and  Water  Heating  and  Ventilating  Apparatus. 


THE   PREPARATION    of  Plans,    Specifications    and   Schedules    for     Heating   and   Ven- 
tilating  by  Hot   Water   or   Steam,   Public    Buildings,  Hospitals  and  Dwelling  Houses, 
by   experienced   engineers,   is   a    specialty  to   which   the   attention    of   Architects  and 
Building   Committees   is   particularly   invited. 


AUTOMATIC  PUMP  AND    ••   •*• 
••   ••   GOVERNOR  COMBINED. 


ro«  RETURNING  HOT  WATER. 
UNDER  PRESSURE.  TO  BOILERS. 
FROM  HIGH  OR  LOW  PRESSURE. 
STEAM  HEATING  SYSTEMS. 


MANUFACTURED    BY 


ALBANY  STEAM  TRAP  Co., 


ALBANY, 
NEW  YORK. 


BLAKE  &  \VILLIAMS, 

STEAM   AND   WATER 

Heating  and  Ventilating  Apparatus, 

No.   197    WOOSXER 


YORK:  CITY. 


E.  RUTZLER, 

HEATING  AND  VENT'LATING  ENGINEER> 

178   CENTRE    STREET,- 

NEW  YORK. 


8vo.  Cloth,  4 1 0  pp.  Price  $5.OO. 


PAVEMENTS   AND    ROADS; 

THEIR 

CONSTRUCTION  AND  MAINTENANCE. 

REPRINTED    FROM 

THE    ENGINEERING    RECORD. 

COMPILED  BY  E.  G.  LOVE,  PH.  D. 


THIS  book  is  a  compilation  of  articles  which  have  appeared  in  recent  volumes  of  THE  ENGINEER- 
ING RECORD,  edited  with  a  view  of  eliminating  whatever  was  of  timely  or  local  interest,  and 
arranged  by  divisions  for  convenience  of  use. 

The  science  of  paving  and  the  need  of  proper  maintenance  of  pavemen  s  is  yet  comparatively 
little  understood  in  this  country,  and  the  same  is  true  in  even  greater  degree  with  regard  to  roads. 
The  editor  of  the  journal  named  was  led  to  give  the  matter  special  attention  by  seeing  what  was 
done  in  Europe,  during  his  visits  there,  and  finally  began  an  investigation  of  work  on  streets  and 
roads  in  England,  France  and  other  countries,  the  result  of  which  was  the  gathering  of  a  large  and 
very  valuable  mass  of  information  in  regard  to  the  subject.  Of  this  everything  likely  to  be  of 
practical  use  in  America  was  printed  in  THE  ENGINEERING  RECORD,  and  is  given  here  in  more 
convenient  shape.  With  it  appears  a  large  quantity  of  matter  from  American  sources,  including  the 
prize  essays  on  Road  Construction  and  Maintenance  submitted  in  the  competition  instituted  by  the 
journal  named  in  December,  1889.  It  will  be  seen  that  the  great  bulk  of  the  book  is  made  up  of  records 
of  experience  and  statements  of  cost  in  different  places.  The  comments  are  based  on  this  experience. 

OF*    CONTENTS. 


PARTI.  Reinstating    Pavements—  Requirements    in 

T     QTmsiTT  T>AVWMT7MT«  New    York—  Maintenance  of   Pavements  in 

ConSrucTfon?fNS  Sve^oFTaving  Inspec-  London-Cleaning  London  Pavements. 

tion-Specifications  in  New  York-  Violation  CHAPTER  VII.-NOTES. 

of  Specifications—  Paving  Material.  Experience  with  Various  Pavements  in  Lon- 
CBT<>  IL-WOO      PAVEMENTS. 


Pavements— Tests  of  Durability— Contracts 
Pavements  in  Paris  and  other  Cities— Sanitary  Guaranteed. 

ROADS:    CONSTRUCTION    AND    MAINTE- 
Nature  and  Uses  of  Asphalt-Pavements  in  Repa£  an^Maintenance-Common  Roads  in 

&&^^^&^^ii%$^     iss^AeE^S&^si 

T?AnA-rcraio     T-n  111 1* tr  KIT  r* «  o     ciit-n-kA*M^t  AOO     Af  tvoaas —  opecincaiions —  legislation —  aviaL- 

rvencw<iis — injury  Dy  VTHS — oiippcrincss — AI-  ad  am    Roads Herscliell'*!  Treatise  on  Road 

fecting  the  Value  of  Property.  Making-Methods   of    Superintending   Con- 

CHAPTER  IV.— BRICK  PAVEMENTS.  struction  and  Repairs. 

Clays,  and  the  Manufacture  of  Paving  Brick  PART  m 

-Crushing  Strength -Use  in  American  Cities  PI?T7W  W<2C  A  VQ  rtM«rtAn  r-rkMCTuiTrTTnTJ 

— Construction   and    Durability  —  Specifica-  rKi^Jt  Jfioa AYo  UN  KUAJJ  CO  Mb  IK.  u  v^  11  uw 

tions-Miscellaneous  Road  Metaling  Material  AND     MAINTENANCE,    submitted    in 

CHAPTERRV^CURBS,    SIDEWALKS     AND  ^SSSfSSSi^ 

Artificial  Stone  for  Curbs— Footpaths  in  Eng- 
land— Asphalt  and  Concrete  for  Footpaths —  jncunuu 
Liverpool  Tramways.  A  Plea  for'  ^Esthetic  Considerations  in  Road 
CHAPTER  VI.— STREET  OPENING— MAINTE-  Making. 

NANCE.  Comments  on  the  Prize  Essays  by  the  Corn- 
Liverpool  Excavation  Contract— Opening  and  mittee  of  Award. 

Sent   Post-paid  on   Receipt  ot   Price. 

ADDRESS,  BOOK  DEPARTMENT. 

THE    ENGINEERING    RECORD, 

277    PEARL   STREET,    NEW    YORK 

(Prior  to  1887,  THE  SANITARY  ENGINEER.) 

Obtainable  at  London  Office,  Q2  and  93  Fleet  Street,  London,  Eng.     Price,  2$s. 


Road  Construction  and  Maintenance. 


The  widespread  interest  in  the  improvement  of  our  highways 

makes  this  little  publication  valuable  to  everybody 

interested  in  the  subject  which  it  treats. 


SOME   PRESS  COMMENTS. 


"  IN  the  year  1890,  THE  ENGINEERING 
RECORD  instituted  a  prize  competition  for 
essays  on  road  making  and  maintenance. 
There  were  21  essays  received,  eight  of 
which  are  reprinted  in  the  book  before  us. 
The  judges  who  made  the  awards  were 
Messrs.  F.  Collingwood,  Edward  P.  North 
and  James  Owen,  and  they  give  some  com- 
ments and  criticism  on  the  papers  presented. 
Ihe  little  book  should  be  in  the  hands 
of  every  road  supervisor,  or  county  board 
having  charge  of  road  making  and  repairs. 
It  will  tell  them  how  to  make  and  keep  a 
good  road,  and  may  have  an  indirect  in- 
fluence in  calling  public  attention  to  the 
need  of  good  roads,  which  awakening  of 
public  opinion  is  more  immediately  needed 
than  the  knowledge  of  how  to  make  the 
roads." — Engineering  and  Mining  Jour- 
nal. 

*  *    *     i.  INTERESTING  particulars  are 
given  as  to  earth,  sand   and  clay  roads, 
and    a    description    of  brick    pavements, 
which,  as  far  as  we  are  aware,  have  not 
been  tried  in  England.     With   regard  to 
the  maintenance  of  macadamized  roads, 
very  great  stress  is  laid  upon  drainage  of 
the  subsoil,  selection  of  the  best  available 
material,   xmstant  repair,  and  the  use  of 
the  steam  roller  is  most  strongly  advo- 
cated, points  which,  we  fear,  are  two  often 
neglected  in  our  own  country  roads.     One 
of  the  essayists  draws  a  parallel  between 
the  civilization  of  a  people  and  the  condi- 
tion of  its  roads.     We  recommend  all  those 
interested    in    the  improvement    of    our 
"ways"  to  obtain  this  little  book." — The 
Builder,  London,  England,  July  9. 

*  *    *     "  VERY  handy  and  fairly  good 
summing  up  of  the  best  modern  practice 
for  country  roads,  particularly  when  read 
with  the  notes  of  the  committee." — Rail- 
road Gazette,  New  York. 


"  ONE  of  the  most  timely  and  interesting 
works  which  has  issued  from  the  technical 
press  of  late,  is  the  one  published  by  THE 
ENGINEERING  RECORD,  of  New  York,  with 
the  title,  '  Road  Construction  and  Main- 
tenance.' This  very  useful  work  is  a  re- 
print from  THE  ENGINEERING  RECORD  of 
three  prize  essays  on  road  making  and 
maintenance.  *  *  *  Popular  and  of 
the  widest  utility.  Another  good  feature 
of  this  work  is  the  criticisms  of  the  essays 
accepted  by  the  judges  or  committee  of 
award,  who  are  well-known,  eminent  civil 
engineers." — Boston  Herald. 

' '  IT  consists  of  several  prize  essays  by 
expert  road  builders  and  engineers,  and  it 
contains  a  vast  amount  of  highly  interest- 
ing and  valuable  information  that  might  be 
useful  to  those  who  are  trying  to  solve  the 
road  problem.  A  clear  understanding  of 
the  views  of  experts  and  practical  men  who 
have  had  experience  is  not  going  to  delay 
the  cause  of  road  reform,  or  hinder  the 
hopes  of  those  who  seek  it.  More  light  on 
the  subject  will  be  useful." — Davenport 
(Iowa)  Democrat. 

*  *  *  "  DESERVE  careful  considera- 
tion in  view  of  the  inferior  character  of 
our  public  roads  compared  with  the  noble 
highways  of  the  leading  European  states. 
These  essays,  the  result  of  a  competition 
instituted  by  THE  ENGINEERING  RECORD, 
are  reprinted  from  that  periodical." — The 
Spy,  Worcester. 

"A  SERIES  of  prize  essays  by  practical 
road  builders,  containing  many  sugges- 
tions of  value  to  highway  commissioners, 
road  superintendents  and  others  inter- 
ested in  the  very  important  matter  of  bet- 
ter roads.  These  essays  were  originally 
printed  in  THE  ENGINEERING' RECORD."— 
Burlington  Hawk-Eye. 


Cloth,  SI.     F»aper,  6O  Cents. 

Sent,  post-paid,  on  receipt  of  price.          Liberal  discount  to  clubs. 

ADDRFSS,  BOOK  DEPARTMENT, 

THE    ENGINEERING    RECORD, 

p.  o.  BOX  3037.  277    PEARL   STREET,    NEW   YORK. 


THE    BERLIN 
VIADUCT    RAILWAY. 

WITH     23     ILLUSTRATIONS. 

REPRINTED    FROM 

THE    ENGINEERING    RECORD. 

(Prior  to  1887,  The  Sanitary  Engineer.} 

PRICE,  25  CENTS.  NEW  YORK,  DECEMBER,  1891. 

ADDRESS,    BOOK    DEPARTMENT, 

ENGINEERING  RECORD, 

277  PEARL  STREET,  NEW  YORK. 


/CONTRACTORS  for  Municipal  and  Government  Work 
and  Manufacturers  of  Engineering  and  Building 
Supplies  will  find  every  week  in  the  Proposal  Ad- 
vertisements and  Contracting  News  columns  of  THE 
ENGINEERING  RECORD  important  items  indicating 
the  wants  of  U.  S.  Government,  Municipal  Author- 
ities, Water  Companies,  and  Building  Committees 
of  Public  Buildings.  Information  will  be  found 
there  each  week  not  elsewhere  published. 


J.  W.  ANDREWS,  E.  H.  JOHNSON,  J.  ROY  ANDREWS, 

President.  Virt>  Pres't&Treas.          Secretary. 

ANDREWS  &  JOHNSON  CO., 

(INCORPORATED) 

ENTIL  ATI  NG^ON  TRACTORS 


c 


AND    MANUFACTURERS  OF 

SHEET  METAL  WORK. 


Our  Specialties:  Exhaust  Fans  and  Johnson's  High 
Speed  Engines.  Mechanical  Ventilation,  Cooling, 
Drying,  Removing  Steam,  Dust,  Smoke,  etc.  ::  ::  :: 

247-247  So.  Jefferson  St.,   CHICAGO. 


WILLIAM  J.  BALDWIN, 


M.  Am.  Soc,  C.  /•;.,  M.  Am.  Soc.  M.  E.,  etc., 


HEATING  AND  VENTILATING  ENGINEER 

AND 

CONTRACTOR, 


o.  277  TE/tRL  STREET, 


YORK. 


AUTHOR  OF  "  STEAM-HEATING  FOR  BUILDINGS  "  (THIRTEENTH  EDITION), 

"  HOT-WATER  HEATING.  AND  FITTING  "  (SECOND  EDITION), 

THE  4<  THERMITS"  PAPERS,  ETC. 

"Plans  and  Estimates  to  Architects, 
^Builders  and  Owners. 


THE  JACKSON 
VENTILATING  GRATE 

Is  admitted  by  authorities  as  being  the  most  per- 
fect ventilator  and  economic  heater  ot  all  open 
fires.  The  back  is  an  air  chamber,  haviner  20 
square  feet  radiating  surface.  Outdoor  air  enter- 
ing this  is  htated,  and  this,  with  the  radiation 
from  the  fire,  will  heat  and  ventilate  7,000  cubic 
feet  space.  53  in  use  in  Harvard  College  ;  65  in 
Pres.  Hospital,  Phila.;  go  in  St.  Paul  Court  House, 
etc.  Send  fur  Catalogue  No.  31. 

EDWIN  A.  JACKSON  &  BRO., 

50   BEEKMAN    STREET,  NEW    YORK. 


PLUMBING  PROBLEMS; 

OR, 

Questions,  Answers  and  ^Descriptions , 


THE   ENGINEERING   RECORD, 

ESTABLISHED   1877. 

(Prior  to  1887,  THE  SANITARY  ENGINEER.) 


With  142  Illustrations. 

"A  feature  of  THE  ENGINEERING  RECORD  (prior  to  1887,  The  Sanitary  Engi- 
neer), is  its  replies  to  questions  on  topics  that  come  within  its  scope,  included  in  which 
are  Water-Supply,  Sewage  Disposal.  Ventilation,  Heating,  Lighting,  House-Drainage 
and  Plumbing.  Repeated  inquiries  concerning  matters  often  explained  in  its  columns, 
suggested  the  desirability  of  putting  in  a  convenient  form  for  reference  a  selection  from 
its  pages  of  questions  and  comments  on  various  problems  met  with  in  house-drainage 
and  plumbing,  improper  work  being  illustrated  and  explained  as  well  as  correct 
methods  It  is.  therefore,  hoped  that  this  book  will  be  useful  to  those  interested  in 
this  branch  of  Sanitary  Engineering." 

TABLE  OF  CONTENTS  : 
DANGEROUS  BLUNDERS  IN  PLUMBING. 


Running  Vent-Pipe  in  Improper  Places — Con- 
necting Soil- Pipes  with  Chimney-Flues — By- 
Passes  in  Trap-Ventilation,  etc.  Illustrated. 

A  Case  of  Reckless  Botching.     Illustrated. 

A  Stupid  Multiplication  of  Traps.  Illustrated. 

Plumbing  Blunders  in  a  Gentleman's  Country 
House.  Illustrated. 

A  Trap  Made  Useless  by  Improper  Adjustment 
of  Inlet  and  Outlet  Pipes.  Illustrated. 

Unreliability  of  Heated  Flue  as  a  Substitute 
for  Proper  Trapping.  Illustrated. 

Need  of  Plans  in  Doing  Plumbing-Work. 

HOUSE-DRAINAGE. 

City  and  Country  House- Drainage — Removal 
of  Ground- Water  from  Houses— Trap-Ventila- 
tion— Fresh-Air  Inlets— Drain-Ventilation  by 
Heated  Flues— Laying  of  Stoneware  Drains. 

Requirements  for  the  Drainage  of  Every  House. 

Drainage  of  a  Saratoga  House.     Illustrated. 

Ground-Water  Drainage  of  a  Country-House. 
Illustrated. 

Ground- Water  Drainage  of  a  City  House.  Il- 
lustrated. 


Fresh -Air  Inlets. 
The    Location   of 
Illustrated. 
Fresh- Air  Inlet 


Fresh-Air  Inlets  in   Cities. 


lying< 
The 


Illustrated. 

Air-Inlets  on  Drains. 

The  Proper  Way  to  Lay  Stoneware  Drains. 

Risks  Attending  the  Omission  of  Traps  and  Re 
on  Drain- Ventilation  by  Flues.  Illustrated. 

The  Tightness  of  Tile-Diains 

Danger  of  Soil-Pipe  Terminals  Freezing  unless 
Ends  are  without  Hoods  or  Cowls. 

Ubject:on    to    Connecting    Bath-Waste    with 
Water-Closet  Trap. 

How  to  Adjust  the  Inlets  and  Outlets  of  Traps. 
Illustrated. 

How  to  Protect  Trap  when  Soil-Pipe  is  used  as 
a  Leader. 

Size  of  Ventilating-Pipes  for  Traps. 

How  to  Prevent  Condensation  Filling   Vent 
Pipes. 

Ventilating  Soil-Pipes. 

How  to  Prevent  Accidental  Discharge  into  Trap 
Vent-Pjpe. 

Why  Traps  should  be  Vented. 


MISCELLANEOUS. 

Syphoning  Water  through  a  Bath-Supply. 
Illustrated. 

Emptying  a  Trap  by  Capillary  Attraction.  Il- 
lustrated. 

As  to  Safety  of  Stop-Cocks  on  Hot  Water 
Pipes. 

How  to  Burnish  Wiped  Joints. 

Admission  to  the  New  York  Trade  Schools. 

Irregular  Water  Supply.     Illustrated. 

Hot  Water  from  the  Cold  Faucet,  and  how  to 
Prevent  it.  Illustrated. 

Disposal  of  Bath  and  Basin  Waste  Water. 

To  Prevent  Corrosion  of  Tank  Lining. 

Number  of  Water  Closets  Required  in  a  Fac- 
tory. 

Size  of  Basin  Wastes  and  Outlets. 

Tar  Coated  Water  Pipe  Affect  Taste  of  Water. 

How  to  Deal  with  Pollution  of  Cellar  Floors. 

How  to  Heat  a  Bathing  Pool. 

Objections  to  Galvanized  Sheet  Iron  Soil  Pipe. 

To  Prevent  Rust  in  a  auction  Pipe. 

Automatic  Shut  Off  for  Gas  Pumping  Engines 
when  Tank  is  Full.  Illustrated. 

Paint  to  Protect  Tank  Linings. 

Vacuum  Valves  not  always  Reliable. 

Size  of  Water  Pipes  in  a  House. 

How  to  Make  Rust  Joints. 

Covering  for  Water  Pipes. 

Size  of  Soil  Pipe  for  an  ordinary  City  House. 

How  to  Construct  a  Sunken  Reservoir  to  Hold 
Two  Thousand  Gallons. 

Where  to  Place  Burners  to  Ventilate  Flues  by 
Gas  Jets.  Illustrated. 

How  to  Prevent  Water  Hammer. 

Why  a  Hydraulic  Ram  does  not  Work. 

Air  in  Water  Pipes. 

Proper  Size  of  Water  Closet  Outlets. 

Is  a  Cement  Floor  Impervious  to  Air  ? 

Two  Traps  to  a  Water  Closet  Objectionable. 

Connecting  Bath  Wastes  to  Water  Closet 
Traps.  Illustrated. 

Objections  to  Leaching  Cesspool  and  need  of 
Fresh  Air  Inlet. 

The  Theory  of  the  Action  of  Field's  Syphon. 

How  to  Disinfect  a  Cesspool. 

Drainage  into  Cesspools. 

Slabs  for  Pantry  Sinks— Wood  vs.  Marbie- 

Test  for  Well  Pollution. 

Cesspool  for  Privy  Vault. 


PLUMBING    PROBLEMS. 


Corrosion  of  Lead  Lining. 

Size  of  Flush  'lank  to  deal  with  Sewage  of  a 
Small  Hospital. 

Details  of  the  Construction  of  a  House-Tank. 
Illustrated. 

The  Construction  of  a  Cistern  under  a  House. 

To  Protect  Lead  Lining  of  a  Tank,  and  Cause 
of  Sweating. 

Stains  on  Marble. 

Lightning  Strikes  Soil  Pipes. 

Will  the  Contents  of  a  Cesspool  Freeze  ? 

Bad  Tast-ng  Water  from  a  Coil.     Illustrated. 

How  to  Fit  Sheet  Lead  in  a  Large  Tank. 

Why  Water  is  "  Milky  "  When  First  Drawn. 

Material  for  Water  Service  Pipes. 

Carving  Tables.     Illustrated. 

Is  Galvanized  Pipe  Dangerous  for  Soft  Spring 
Water. 

How  to  Arrange  Hush  Pipes  in  Cisterns  to  Pre- 
vent Syphoning  Water  Through  Ball  Cock. 

Depth  of  Foundations  to  Prevent  Dampness  of 
Site. 

Where  to  Place  a  Tank  to  get  Good  Discharge 
at  Faucet. 

Self  Acting  Water  Closets.     Illustrated. 

Wind  Disturbing  Seal  of  Trap. 

How  to  Draw  Water  from  a  Deep  Well. 

Cause  of  Smell  of  Well  Water.  '    . 

Absorption  of  Light  by  Gas  Globes. 

Defective  Drainage.     Illustrated. 

fitting  Basins  to  Marble  Slabs.   Illustrated. 

Intermediate  Tanks  for  the  Water  Supply  of 
High  Buildings.  Illustrated. 

How  to  Construct  a  Filtering  Cistern.  Illus- 
trated. 

Objections  to  Running  Ventilating  Pipe  Into 
Chimney-Flue. 

Size  of  Water  Supply  Pipe  for  Dwelling  House. 

Faulty  Plan  of  a  Cesspool.     Illustrated. 

Connecting  Refrigerator  Wastes  with  Drains. 
Illustrated. 

Disposing  of  Refrigerator  Wastes.  Illustrated. 

Pumping  Air  From  Water  Closet  into  Tea 
Kettle  as  Result  of  Direct  Supply  to  Water 
Closets.  Illustrated. 

Danger  in  Connecting  Tank  Overflows  with 
Soil  Pipes. 

Arrangement  of  Safe  Wastes.    Illustrated. 

The  kind  of  Men  Who  do  not  Like  the  Sani- 
tary Engineer 

What  is  Reasonable  Plumbers'  Profit. 

HOT  WATER  CIRCULATION  IN  BUILD- 
INGS. 

Bath  Boilers.     Illustrated. 

Setting  Horizontal  Boilers.     Illustrated. 


How  to  Secure  Circulation  Between  Boilers  in 
Different  Houses.  Illustrated. 

Connecting  One  Boiler  with  Two  Ranges. 
Illustrated. 

Taking  Return  Below  Boiler.     Illustrated. 

Trouble  with  Boiler. 

An  Ignorant  Way  of  Dealing  with  a  Kitchen 
Boiler.  Illustrated. 

Returning  into  Hot  Water  Supply  Pipe.  Illus- 
trated. 

Where  should  Sediment  Pipe  from  Boiler  be 
connected  with  Waste-Pipe  ? 

Several  Flow  Pipes  and  one  Circulation  Pipe. 
Illustrated. 

How  to  Run  Pipes  from  Water  Back  to  Boiler. 
Illustrated. 

Hot  Water  Circulation  when  Pipes  from  Boiler 
pass  under  the  Floor.  Illustrated. 

Heating  a  Room  from  Water  Back. 

The  Operation  of  Vacuum  and  Safety  Valves. 
Illustrated. 

Preventing  Collapse  of  Boilers. 

Collapse  of  a  Boiler.     Illustrated. 

Explosion  of  Water  Backs. 

A  Proposed  Precaution  against  Water  Back 
Explosions.  Illustrated. 

The  Bursting  of  Kitchen  Boilers  and  Connect- 
ing Pipes.  Illustrated. 

Giving  but  of  Lead  Vent  Pipes  from  Boilers  in 
an  Apartment  House.  Illustrated. 

Connecting  a  Kitchen  Boiler  with  One  or  More 
Water  Backs.  Illustrated. 

New  Method  of  Heating  Two  Boilers  by  One 
Water  Back.  Illustrated. 

Plan  of  Horizontal  Hot  Water  Boiler.  Illus- 
trated. 

HOT    WATER    SUPPLY    IN    VARIOUS 
BUILDINGS. 

Kitchen  and  Hot  Water  Supply  in  the  Resi- 
dence of  Mr.  W.  K.  Vanderbilt,  New  York. 
Illustrated. 

Kitchen  and  Hot  Water  Supply  in  the  Resi- 
dence of  Mr.  Cornelius  Vanderbilt,  New  York. 
Illustrated. 

Kitchen  and  Hot  Water  Supply  in  the  Resi- 
dence of  Mr.  Henry  G.  Marquand,  New  York. 
Illustrated. 

Kitchen  and  Hot  Water  Supply  in  the  Resi- 
dence of  Mr.  A.  J.  White.  Illustrated. 

Hot  Water  Supply  man  Office  Building.  Illus- 
trated. 

Kitchen  and  Hot  Water  Supply  in  the  Resi- 
dence of  Mr.  Sidney  Webster.  Illustrated. 

Plumbing  and  Water  Supply  in  the  Residence 
of  Mr.  H.  H.  Cook.  Illustrated. 


Large  8vo.  cloth,  $2.00. 
Address,  BOOK  DEPARTMENT, 

THE    ENGINEERING    RECORD, 

p.  o.  BOX  3037.  277  PEARL  STREET,  NEW  YORK. 


THEJUCHMOND 

STEAMJVND     . 

H  O  T- WATER  HE  AT  E  R  S 

HAVE  A  NATIONAL 

REPUTATION. 


The  Most 

Complete 

Line. 


Capacities 

from 

100  to  4,000 

Feet. 


We 

Protect 

Agents 

Fully 

and  do 

No 

Contracting 

Ourselves. 


SOLD  a  TO  «  THE  «  TRADE  «  ONLY. 


/or  Atew  Catalogue  and  P rice-List. 


ADDRESS 


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STOVE  COMPANY, 

NORWICH,  CONN. 


MAKE  YOUR  HOME  COMFORTABLE 

BY    USING 

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(Trade  Mark.) 

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-  AND  IN- 

EVERY  WAY  SUPERIOR  TO  OTHERS. 


Examine  Our  Extensive  Assortment  Before 
Placing  Orders. 


SEND  FOR  ILLUSTRATED  CATALOGUE. 


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